Self-Instructional Manual for Chemistry for Engineers PDF

UNIVERSITY OF MINDANAO College of Engineering Education Chemical Engineering Program Physically Distanced but Academically Engaged Self-Instructional Manual (SIM) for Self-Directed Learning (SDL) Course/Subject: BCHE 111/L – CHEMISTRY FOR ENGINEERS...

UNIVERSITY OF MINDANAO College of Engineering Education Chemical Engineering Program Physically Distanced but Academically Engaged Self-Instructional Manual (SIM) for Self-Directed Learning (SDL) Course/Subject: BCHE 111/L – CHEMISTRY FOR ENGINEERS Name of Author: Engr. Jay Carlo S. Aguilar THIS SIM/SDL MANUAL IS A DRAFT VERSION ONLY; NOT FOR REPRODUCTION AND DISTRIBUTION OUTSIDE OF ITS INTENDED USE. THIS IS INTENDED ONLY FOR THE USE OF THE STUDENTS WHO ARE OFFICIALLY ENROLLED IN THE COURSE/SUBJECT. EXPECT REVISIONS OF THE MANUAL.  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Table of Contents Big Picture 1...................................................................................................................................... 6 Big Picture in Focus: ULO1a.............................................................................................................. 6 Metalanguage............................................................................................................................ 6 Essential Knowledge.................................................................................................................. 6 Self-Help................................................................................................................................... 15 Let’s Check............................................................................................................................... 16 Let’s Analyze............................................................................................................................ 16 In a Nutshell............................................................................................................................. 16 Keywords Index........................................................................................................................ 16 References............................................................................................................................... 16 Big Picture in Focus: ULO1b............................................................................................................ 17 Metalanguage.......................................................................................................................... 17 Essential Knowledge................................................................................................................ 19 Self-Help................................................................................................................................... 66 Let’s Check............................................................................................................................... 67 Let’s Analyze............................................................................................................................ 67 In a Nutshell............................................................................................................................. 67 Keywords Index........................................................................................................................ 67 References............................................................................................................................... 67 Course Schedule....................................................................................................................... 71 Big Picture 2.................................................................................................................................... 72 Big Picture in Focus: ULO2a............................................................................................................ 72 Metalanguage.......................................................................................................................... 72 Essential Knowledge................................................................................................................. 73 Self-Help................................................................................................................................... 84 Let’s Check............................................................................................................................... 84 Let’s Analyze............................................................................................................................. 84 In a Nutshell............................................................................................................................. 84 Keywords Index........................................................................................................................ 85 References............................................................................................................................... 85 Big Picture in Focus: ULO2b............................................................................................................ 86 Metalanguage.......................................................................................................................... 86  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Essential Knowledge................................................................................................................. 87 Self-Help................................................................................................................................... 94 Let’s Check............................................................................................................................... 94 Let’s Analyze............................................................................................................................. 95 In a Nutshell............................................................................................................................. 95 Keywords Index........................................................................................................................ 95 References............................................................................................................................... 95 Big Picture in Focus: ULO2c............................................................................................................ 97 Metalanguage.......................................................................................................................... 97 Essential Knowledge................................................................................................................. 97 Self-Help................................................................................................................................. 112 Let’s Check............................................................................................................................. 112 Let’s Analyze........................................................................................................................... 112 In a Nutshell........................................................................................................................... 112 Keywords Index...................................................................................................................... 113 References............................................................................................................................. 113 Big Picture in Focus: ULO2d.......................................................................................................... 114 Metalanguage........................................................................................................................ 114 Essential Knowledge............................................................................................................... 115 Self-Help................................................................................................................................. 127 Let’s Check............................................................................................................................. 127 Let’s Analyze........................................................................................................................... 127 In a Nutshell........................................................................................................................... 128 Keywords Index...................................................................................................................... 128 References............................................................................................................................. 128 Course Schedule..................................................................................................................... 131 Big Picture 3.................................................................................................................................. 132 Big Picture in Focus: ULO3a.......................................................................................................... 132 Metalanguage........................................................................................................................ 132 Essential Knowledge............................................................................................................... 134 Self-Help................................................................................................................................. 140 Let’s Check............................................................................................................................. 140 Let’s Analyze........................................................................................................................... 140 In a Nutshell........................................................................................................................... 141  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Keywords Index...................................................................................................................... 141 References............................................................................................................................. 141 Big Picture in Focus: ULO3b.......................................................................................................... 143 Metalanguage........................................................................................................................ 143 Essential Knowledge............................................................................................................... 144 Self-Help................................................................................................................................. 157 Let’s Check............................................................................................................................. 157 Let’s Analyze........................................................................................................................... 157 In a Nutshell........................................................................................................................... 158 Keywords Index...................................................................................................................... 158 References............................................................................................................................. 158 Big Picture in Focus: ULO3c.......................................................................................................... 161 Metalanguage........................................................................................................................ 161 Essential Knowledge............................................................................................................... 162 Self-Help................................................................................................................................. 172 Let’s Check............................................................................................................................. 172 Let’s Analyze........................................................................................................................... 172 In a Nutshell........................................................................................................................... 172 Keywords Index...................................................................................................................... 173 References............................................................................................................................. 173 Course Schedule..................................................................................................................... 174 Big Picture 4.................................................................................................................................. 175 Big Picture in Focus: ULO4a.......................................................................................................... 175 Metalanguage........................................................................................................................ 175 Essential Knowledge.............................................................................................................. 177 Self-Help................................................................................................................................. 185 Let’s Check............................................................................................................................. 186 Let’s Analyze.......................................................................................................................... 186 In a Nutshell........................................................................................................................... 187 Keywords Index...................................................................................................................... 187 References............................................................................................................................. 187 Big Picture in Focus: ULO4b.......................................................................................................... 190 Metalanguage........................................................................................................................ 190 Essential Knowledge.............................................................................................................. 191  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Self-Help................................................................................................................................. 205 Let’s Check............................................................................................................................. 205 Let’s Analyze.......................................................................................................................... 206 In a Nutshell........................................................................................................................... 206 Keywords Index...................................................................................................................... 207 References............................................................................................................................. 207 Big Picture in Focus: ULO4c.......................................................................................................... 209 Metalanguage........................................................................................................................ 209 Essential Knowledge.............................................................................................................. 210 Self-Help................................................................................................................................. 220 Let’s Check............................................................................................................................. 220 Let’s Analyze.......................................................................................................................... 220 In a Nutshell........................................................................................................................... 221 Keywords Index...................................................................................................................... 222 References............................................................................................................................. 222 Big Picture in Focus: ULO4d.......................................................................................................... 225 Metalanguage........................................................................................................................ 225 Essential Knowledge.............................................................................................................. 227 Self-Help................................................................................................................................. 236 Let’s Check............................................................................................................................. 237 Let’s Analyze.......................................................................................................................... 237 In a Nutshell........................................................................................................................... 238 Keywords Index...................................................................................................................... 238 References............................................................................................................................. 238 Course Schedule..................................................................................................................... 239  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Course Outline: BCHE 111/L – CHEMISTRY FOR ENGINEERS Course Coordinator: Engr. Jeralyn G. Cabotaje Email: [email protected] Student Consultation: Done by online (LMS), emails, face to face Mobile: Phone: 2961084 local 133 Effectivity Date: August 2, 2022 Mode of Delivery: Blended (On-Line with face to face or virtual sessions) Time Frame: 108 Hours (Lecture+Laboratory) Student Workload: Expected Self-Directed Learning Requisites: None Credit: 4 units (3 units lecture, 1 unit laboratory) Attendance Requirements: A minimum of 95% attendance is required at all scheduled Virtual or face to face sessions. Course Outline Policy Areas of Concern Details Contact and Non-contact Hours This 4-unit course self-instructional manual is designed for blended learning mode of instructional delivery with scheduled face to face or virtual sessions. The expected number of hours will be 108 including the face to face or virtual sessions, and laboratory. The face to face sessions shall include the summative assessment tasks (exams) since this course is crucial in the licensure examination for engineers. 1  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Assessment Task Submission Submission of assessment tasks shall be on 3rd, 5th, 7th and 9th week of the term. The assessment paper shall be attached with a cover page indicating the title of the assessment task (if the task is performance), the name of the course coordinator, date of submission and name of the student. All submissions should be done through Blackboard. It is also expected that you already paid your tuition and other fees before the submission of the assessment task. If the assessment task is done in real time through the features in the Blackboard Learning Management System, the schedule shall be arranged ahead of time by the course coordinator. Penalties for Late The score for an assessment item submitted after the Assignments/Assessments designated time on the due date, without an approved extension of time, will be reduced by 5% of the possible maximum score for that assessment item for each day or part day that the assessment item is late. However, if the late submission of assessment paper has a valid reason, a letter of explanation should be submitted and approved by the course coordinator. If necessary, you will also be required to present/attach evidences. Return of Assignments/ Assessment tasks will be returned to you two (2) weeks Assessments after the submission. This will be returned by email or via Blackboard portal. For group assessment tasks, the course coordinator will require some or few of the students for online or virtual sessions to ask clarificatory questions to validate the originality of the assessment task submitted and to ensure that all the group members are involved. Assignment Resubmission You should request in writing addressed to the course coordinator his/her intention to resubmit an assessment task. The resubmission is premised on the student’s failure to comply with the similarity index and other reasonable grounds such as academic literacy standards or other reasonable circumstances e.g. illness, accidents financial constraints. 2  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Re-marking of Assessment Papers You should request in writing addressed to the program and Appeal coordinator your intention to appeal or contest the score given to an assessment task. The letter should explicitly explain the reasons/points to contest the grade. The program coordinator shall communicate with the students on the approval and disapproval of the request. If disapproved by the course coordinator, you can elevate your case to the program head or the dean with the original letter of request. The final decision will come from the dean of the college. Grading System All culled from BlackBoard sessions and traditional contact Course discussions/exercises – 30% 1st formative assessment – 10% 2nd formative assessment – 10% 3rd formative assessment – 10% All culled from on-campus/onsite sessions (TBA): Final exam – 40% Submission of the final grades shall follow the usual University system and procedures. Preferred Referencing Style IEEE Student Communication You are required to create a umindanao email account which is a requirement to access the BlackBoard portal. Then, the course coordinator shall enroll the students to have access to the materials and resources of the course. All communication formats: chat, submission of assessment tasks, requests etc. shall be through the portal and other university recognized platforms. You can also meet the course coordinator in person through the scheduled face to face sessions to raise your issues and concerns. For students who have not created their student email, please contact the course coordinator or program head. Contact Details of the Dean Dr. Charlito L. Canesares Email: [email protected] Phone: 09562082442 3  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Contact Details of the Program Engr. Jay Carlo Aguilar Head Email: [email protected] Students with Special Needs Students with special needs shall communicate with the course coordinator about the nature of his or her special needs. Depending on the nature of the need, the course coordinator with the approval of the program coordinator may provide alternative assessment tasks or extension of the deadline of submission of assessment tasks. However, the alternative assessment tasks should still be in the service of achieving the desired course learning outcomes. Online Tutorial Registration Platforms such as Google Meet and Zoom (whichever is convenient) will be used for video conference. Kindly create an account ahead of time. Help Desk Contact CEE Jessica Dagohoy [email protected] 09562082442 082-2272902 GSTC Ronadora E. Deala, RPsy, RPm, RGC, LPT [email protected] 09212122846 Silvino P. Josol [email protected] 09060757721 Library Contact LIC Brigida E. Bacani [email protected] 09513766681 4  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Course Information – see/download course syllabus in the Black Board LMS CC’s Voice: Hello engineer in the making! Welcome to this course BCHE 111/L: Chemistry for Engineers. This course deals with core concepts of chemistry which are important in the practice of engineering profession which includes generation of energy, the chemistry of engineering materials, the chemistry of the environment and a special topic specific to an engineering field of expertise. CO CO stands for Course Outcomes. These are the skills that students are expected to demonstrate at the end of the course to pass the subject. The following are the COs of BCHE 111/L: CO 1. Demonstrate understanding of chemistry in relation to the generation of energy, the chemical principles and concepts of structures and bonding of common engineering materials, and the chemical processes that take place in the environment. CO 2. Conduct experiments in relation to the models and concepts learned in class. Let us begin! 5  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Big Picture 1 Week 1-3: Unit Learning Outcomes (ULO): At the end of the unit, you are expected to a. Perform conversion of units b. demonstrate understanding of the concepts of chemical safety. Big Picture in Focus: ULO1a. perform conversion of units. Metalanguage In this section, the most essential principles and concepts relevant to the study of chemical safety to demonstrate ULO1a will be reviewed. Please refer to these definitions in case you will encounter difficulty in understanding educational concepts. Dimension are physical quantities that can be measured (e.g. length, volume) Units are arbitrary names that correlate to particular dimensions to make the measurement relative to an agreed upon definition (e.g. meter, liter) Conversion Factor a number used to change one set of units to another, by multiplying or dividing Scientific Notation a way of expressing numbers that are too large or too small to be conveniently written in decimal form Essential Knowledge STANDARDS AND MEASUREMENT Communication sometimes requires a method of expressing sizes that are easily understood. The measurements are used in calculations to obtain other related quantities. Measurement in simple cases means comparing a thing with a standard to see how many times as big it is. It is important to have standards that are precisely defined and that are used in common by people involved in trade, science, and industry. 6  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 This section points out the importance of taking a measurement, both in the laboratory and in day–to–day life. Weight, volume, and temperature are examples of variable measured by chemists. Reading a Measuring Device There are two ways that devices can indicate a value: digital and non-digital. 1. The digital device (shown below) gives the mass of the object in grams. Laboratory workers record this value as the mass of the object. 2. Many devices in a laboratory are non-digital. An example of this is the ruler below. The line measures between 3 & 4. The black lines are the calibration lines. How can this value become more accurate (closer to the true value)? 1 2 3 4 The ruler reads between 3.5 and 3.6, but the value seems closer to 3.6. It seems reasonable to call it 3.59. The statement below is the fundamental rule of measurement. “When recording a reading from a digital measuring device, record all the digits shown. When recording a reading from a non-digital device, write down all the digits that are known with certainty plus one that is estimated.” Significant Figures Not all of the figures in a value are always “significant”; that is, they are not always included in the actual measured value. The following are rules on how to deal with significant digits when rounding numbers & using scientific notation. 1. Rounding 7  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Rounding is the removal of digits in a number when it is necessary to express the number with fewer digits. When these digits have been dropped, the final digit must be “rounded”, either up or down, as shown below: A. Rounding down: If the number just after the last significant figure (or digit) is less than 5, the significant figure is rounded down (or as the text states, not rounding up). For example, 54.623 rounded to 4 digits would be 54.62 B. Rounding up: If the number just after the last significant figure (or digit) is greater than 5, the significant figure is rounded up: 54.528 rounded to 4 digits would be 54.53 C. Even/Odd Rule: This is only used occasionally & is one of two ways that are used in dealing with the number after the last significant figure being equal to 5. Round the five so the last figure is even. For example, 54.625 rounded to 4 digits would be 54.62 54.635 rounded to 4 digits would be 54.64 Examples: Round the following measurements. Report the answer with the proper units. a. 107.77 degrees Celsius to 4 digits  107.8°C b. 6.53300 grams to 5 digits  6.5330 g c. 28.6 grams/milliliter to 2 digits  29 g/mL d. 48.67305 nanometers to 6 digits  48.6730 nm 2. Scientific Notation Scientific notation is used as a way to make expressing numbers more manageable. A number expressed in scientific notation has a value multiplied by 10 to some power. 1000 = 1 x 103 The value is “1”. This is multiplied by 103, or 10 x 10 x 10 = 1000. So 1 x 1000 = 1000 2000 = 2 x 103 5400 = 5.4 x 103 Just as numbers greater than one can be converted to scientific notation, numbers less than one can also be converted into scientific notation. Keep in mind that 10 – 1 = 1/10 = 0.1. 0.001 = 1 x 10 – 3 The value is “1”. This is multiplied by 10 – 3, or 0.1 x 0.1 x 0.1 = 0.001. So 1 x 0.001 = 0.001. When expressing numbers in scientific notation, it is preferable to keep the value between 1 and 10 as was done in the previous three cases. Examples: 8  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Express the following numbers in scientific notation. 1. 9,200,000,000,000,000,000,000,000  9.2 x 1024 2. 73400000  7.34 x 107 3. 0.000048  4.8 x 10 – 5 4. 0.000000006688  6.688 x 10 – 9 3. Rules for the Number of Significant Figures Recording data measurements to the proper number of significant figures gives others who look at the data a sense of how accurate the readings were. When manipulating data, carry significant figures forward in different ways depending on the mathematics that are done. 1. Any non-zero digit is significant. 56.783 has 5 significant figures. 2. Any zero located between two numbers is significant. 402.6 has 4 significant figures. 3. Any zero to the left of non-zero digits is not significant unless it is covered by #2. 0.06034 has 4 significant digits. 4. Any zero to the right of non-zero digits and also to the right of a decimal point is significant. 812.90 has 5 significant figures. 5. Any zero to the right of non-zero digits & to the left of a decimal point (& not covered by #2) may, or may not be, significant, depending on whether the zero is placeholder or was actually part of a measurement. To be as clear as possible, express such values using scientific notation. The number 150900 has either 4, 5, or 6 significant figures. However, if the scientist expresses the data point like this: 1.5090 x 105, then the number has 5 significant figures (Rule #4). Examples: Give the number of significant figures in each of the following values: a. 69.4703 mL  6 significant figures b. 0.00071 g  2 significant figures; the leading zeros are not important c. 0.03300 s  4 significant figures; the trailing zeros are important A physical quantity is any number that is used to describe a physical phenomenon quantitatively. Fundamental (or base) quantities are the simplest types of quantities and cannot be reduced further. Quantity Unit 1. Length, L Meter, m 2. Mass, m, or Weight, W Kilogram, kg 3. Time, t Second, s 4. Temperature, T Kelvin, K 5. Electric current, I Ampere, A 9  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Table 2. 6. Amount of substance, n Mole, mol 7. Luminous intensity Candela, cd Derived quantities are based on combinations of the fundamental quantities. Ex. 1. velocity, L/t  m/s ; km/h 2. volume, L3  m3; cm3; ft3 3. area, L2  m2; yd2 4. density, m/V  g/cm3; kg/m3; lb/ft3 A system of units is a complete set of units, both fundamental and derived, for all kinds of quantities. 1. English system 2. Metric system (SI) The Metric System The metric system, or International System (SI, from (Systemé Internationale), is a decimal system of units for measurements of mass, length, time, and other physical quantities. It is built around a set of standard units and uses factors of 10 to express larger or smaller numbers of these units, & prefixes are added to the names of the units. These prefixes represent multiples of 10, making the metric system a decimal system of measurements. The metric system is superior to the English system in the area of interrelationships between units because it is less complicated being a decimal unit system. In this system, conversion from one unit size to another can be accomplished by moving the decimal point to the right or left at an appropriate number of places. It is founded on 7 base units and 2 supplementary units (see Table 2 above). The various units for a quantity are always related by factors of ten. The metric system is currently used by most of the countries in the world, not only in scientific and technical work but also in commerce and industry. Powers (or factors) of ten is used to express very large or very small numbers, more conveniently, in an abbreviated form. This is done by the use of prefixes (see Table 3). Conversions between and within the system of units can be made by use of a very few conversion factors. 10  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Conversion factors (cf) are the factors that relate 2 different units of the same quantity (unit1 and unit2). Important equation for conversion: unit2 = unit1 (conversion factor) Where: unit1 = is the given unit unit2 = is the desired unit The conversion factor must accomplish 2 things: 1. it must cancel (or eliminate) the original unit1, & 2. must introduce the new unit2 ⎯ the unit wanted in the answer. Ex: the conversion factor 1 km = = 103m = 1000 m can be written into 2 ways: 1 km 1000 m or 1000 m 1 km Table 3. Table below shows the names, symbols, and numerical values of the prefixes. Prefix Symbol Numerical Value Power of 10 equivalent exa E 1,000,000,000,000,000,000 1018 peta P 1,000,000,000,000,000 1015 tera T 1,000,000,000,000 1012 giga G 1,000,000,000 109 mega M 1,000,000 106 kilo k 1,000 103 hecto h 100 102 deka da 10 101 Base unit ⎯ 1 100 deci d 0.1 10 – 1 centi c 0.01 10 – 2 milli m 0.001 10 – 3 micro  0.000001 10 – 6 nano n 0.000000001 10 – 9 pico p 0.000000000001 10 – 12 femto f 0.000000000000001 10 – 15 atto a 0.000000000000000001 10 – 18 Some Common Conversion Factors I Length 1 kilometer (km) = 0.6214 mile (mi) 1 meter (m) = 100 centimeter (cm) = 39.37 inches (in) = 3.28 feet (ft) 1 mile (mi) = 5280 feet (ft) = 1760 yards (yd) = 1.6093 km = 1609.3 m 1 inch (in) = 2.54 cm = 25.4 mm 1 yard (yd) = 3 feet (ft) = 0.9146 m 1 feet (ft) = 12 inches (in) 1 angstrom (Å) = 10 – 10 m 11  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 II Mass/Weight 1 kilogram (kg) = 2.205 pounds (lb) 1 pound (lb) = 453.6 g = 0.4536 kg 1 pound (lb) = 16 oz 1 oz = 28.35 g 1 metric ton (T) = 1000 kg = 2205 lb 1 US short ton = 907 kg = 2000 lb 1 British long ton = 1016 kg = 2240 lb ; 1 atomic mass unit (u) = 1.6606 x 10 – 27 kg III Volume 1 liter (L) = 1000 milliliter (mL) = 10 – 3 m3 = 1 dm3 = 1.06 quarts (qt) = 0.0353 cubic ft (ft3) 1 mL = 1 cubic cm (cc or cm3) 1 US gallon (gal) = 3.785 L 1 US gallon (gal) = 4 quarts (qt) = 8 pints (pt) 1 quart (qt) = 32 fluid ounces (fl oz) = 0.946 liter (L) 1 fl. oz. = 29.6 mL 1 ft3 = 28.32 ; 1 m3 = 35.3 ft3 IV Area 1 yd2 = 0.836 m2 ; 1 cm2 = 0.155 in2 ; 1 km2 = 1.196 x 10 6 yd2 1 acre = 4840 yd2 = 4046.556 m2 1 hectare (ha) = 2.471 acres = 10,000 m2 V Energy 1 calorie (cal) = 4.184 joules (J) 1 British Thermal Unit (BTU) = 252 cal = 1055 J VI Pressure 1 Pascal (Pa) = 1 kg/m s2 ; 1kPa = 1000 Pa 1 atmosphere (atm) = 760 torr = 760 mm Hg = 101,325 Pa = 14.7 in Hg Mass and Weight Before introducing the base unit used to define mass, consider one important issue, distinguishing the difference between weight and mass. Weight & mass are not the same. Mass measures the amount of matter in an object/substance; it is constant throughout the universe. Weight measures the effect the gravity (attraction from another body) on an object. It is related to mass (since it acts on it), yet weight varies from one planet & star to 12  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 another, because different objects pose different gravitational (attractive) forces on the same mass. Therefore, the weight of an object will vary depending on where it is. Volume, as used, is the amount of space occupied by matter. The most common instruments or equipment for measuring volume of liquids are the graduated cylinder, volumetric flask, burette, pipette, and syringe. A liter, L, is usually defined as a cubic decimeter (1 dm3) of water at 4°C. DENSITY Density, , indicates the amount of mass per volume of a specific substance. Such a measurement is very helpful because two different substances rarely have the exact same density. Therefore, density can be used to distinguish unknown substances from one another & help in identifying them. is given by the equation 𝑚𝑎𝑠𝑠, 𝑚 𝑚 𝐷𝑒𝑛𝑠𝑖𝑡𝑦, 𝜌 = = 𝑣𝑜𝑙𝑢𝑚𝑒, 𝑉 𝑉 Alternate forms: 𝑚 𝑉= or 𝑚 = 𝜌𝑉 𝜌 The density of water at 4°C is 1.0000 g/mL or 1.0000 g/cm3 or 1000.00 kg/m3 or 62.4 lb/ft3. Densities for liquids and solids are usually represented in terms of g/mL or g/cm3. The density of gases, however, is expressed in terms of g/L. The specific gravity (sp gr) of a substance is the ratio of the density of that substance to the density of another substance, usually water at 4°C. The specific gravity tells us how many times as heavy a liquid, a solid, or a gas is as compared to the reference material. Since the density of water at 4°C is 1.00 g/mL, the specific gravity of a solid or liquid is the same as its density in g/ml without the units. 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒 𝑆. 𝐺. 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒 = 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟 Alternate form: 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒 = (𝑆. 𝐺. 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒)(𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟) When an insoluble solid object is dropped into water, it will sink or float, depending on its density. If the object is less dense than water, it will float, displacing a mass of water equal to the mass of the object. If the object is more dense than 13  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 water, it will sink, displacing a volume of water equal to the volume of the object. This information can be utilized to determine the volume (and density) of irregularly shaped objects. Table 4. Densities of Some Selected Materials Liquids and Solids Gases Substance Density Substance Density (g/mL at 20°C) (g/mL at 0°C) Wood (Douglas fir) 0.512 Hydrogen 0.090 Ethyl alcohol 0.789 Helium 0.178 Vegetable oil 0.91 Methane 0.714 Water (4°C) 1.000 Ammonia 0.771 Sugar 1.59 Neon 0.90 Glycerin 1.26 Carbon monoxide 1.25 Karo Syrup 1.37 Nitrogen 1.251 Sulfuric acid 1.84 Air 1.293 Sulfur 2.07 Oxygen 1.429 Salt 2.16 Hydrogen chloride 1.63 Aluminum 2.70 Argon 1.78 Silver 10.5 Carbon dioxide 1.963 Lead 11.34 Chlorine 3.17 Mercury 13.55 Gold 19.3 Note: For comparing densities the density of water is the reference for solids and liquids; air is the reference for gases. TEMPERATURE SCALES Temperature is a measure of the hotness or coldness of an object. It is that property of matter that determines the direction of heat transfer. Heat can flow only from a body at a higher temperature to one at a lower temperature. Temperature does not measure the amount of heat present in an object/substance. The temperature of an object is measured by one of the four scales, ▪ Celsius (or Centigrade) ▪ Fahrenheit ▪ Kelvin ▪ Rankine Scientists everywhere measure temperature in terms of the Celsius scale. Though not an SI unit, the Celsius scale may be used with SI units. The Celsius scale divides the range between the freezing point (0°C) & boiling point(100°C) of water into 100degrees. The Fahrenheit scale, which is the most commonly used 14  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 scale in the United States outside the laboratory, defines the normal freezing & boiling points of water to be exactly 32°F & 212°F, respectively. Thermometer is the most common instrument used for measuring temperature. Comparison of the Three Temperature Scales Conversion of Temperature Scales (a) from Celsius to Fahrenheit (b) from Fahrenheit to Celsius TC = 59 (TF − 32) Absolute Scales T R = T F + 460 TK = T C + 273 Self-Help: You can also refer to the sources below to help you further understand the lesson. Serway, R. (2014). Physics for Scientist and Engineers with Modern Physics (9th ed) Australia: Cengage Learning. 15  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Let’s Check For #s 1-3, round the following measurements. Report the answer with the proper units. 1. 7.8177 rounded to the nearest tenth 2. 1.0643 rounded to the nearest hundredth 3. 3.8781 rounded to the nearest thousandth 4. Write 13.378162 correct to 4 significant digits. 5. Write 75.378212 correct to 3 significant digits/figures. Let’s Analyze Express the following numbers in scientific notation. (Note: When expressing numbers in scientific notation, it is preferable to keep the value between 1 and 10 as was done in the previous three cases.) 1. 1,181,995 2. 10,279,191 3. 873,490,238 4. 2,348,992,374 5. 49,810,823,012 In a Nutshell 1. Convert 312 oC to oR. 2. Convert 2.5 meters to yards. 3. Convert 4 liters to cm3. 4. Convert 149 cm2 to in2. 5. Convert 510 oR to K. Keywords Index Dimension Units Conversion Factor Scientific Notation References Serway, R. (2014). Physics for Scientist and Engineers with Modern Physics (9th ed) Australia: Cengage Learning. 16  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Big Picture in Focus: ULO1b. demonstrate understanding of the concepts of chemical safety. Metalanguage In this section, the most essential principles and concepts relevant to the study of chemical safety to demonstrate ULO1b will be reviewed. Please refer to these definitions in case you will encounter difficulty in understanding educational concepts. Accident defined as an unplanned event leading to undesired consequences Acute toxicity describes the adverse effects of a substance that result either from a single exposure or from multiple exposures in a short period of time (usually less than 24 hours) Biohazard a biological substance that poses a threat to the health of living organisms, primarily humans. This could include a sample of a microorganism, virus or toxin that can adversely affect human health. Carcinogen any substance, radionuclide, or radiation that promotes carcinogenesis, the formation of cancer Chemical the control of exposure to potentially hazardous substances to attain laboratory an acceptably low risk of exposure safety Chronic toxicity the development of adverse effects as the result of long term exposure to a toxicant or other stressor Corrosives are chemicals which cause burns on the skin, mucous membrane and eyes Dermatotoxin a toxic chemical that damages skin, mucous membranes, or both, often leading to tissue necrosis Explosive a solid or liquid chemical which is in itself capable by chemical reaction of producing gas at such a temperature and pressure and at such a speed to cause damage to the surroundings Flammable gases, liquids and solids that will ignite and continue to burn in air if exposed to a source of ignition Flash point The minimum temperature at which a liquid gives off enough vapor to form an ignitable mixture Fume Hood a ventilated enclosure in which gases, vapors and fumes are contained. An exhaust fan situated on the top of the laboratory building pulls air and airborne contaminants through connected ductwork and exhausts them to the atmosphere. GHS Stands for Globally Harmonized System. It is a system for standardizing and harmonizing the classification and labeling of chemicals. 17  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Hazard defined as a chemical or physical condition that has the potential for causing damage to people, property, or the environment Hematotoxins toxins that destroy red blood cells, disrupt blood clotting, and/or cause organ degeneration and generalized tissue damage. Hepatotoxins a toxic chemical substance that damages the liver Incident the unexpected release of a substance that is (potentially) hazardous either to humans, other animals or the environment LC50 LC stands for "Lethal Concentration". LC values usually refer to the concentration of a chemical in air but in environmental studies it can also mean the concentration of a chemical in water. The concentrations of the chemical in air that kills 50% of the test animals during the observation period is the LC50 value. LD50 LD stands for "Lethal Dose". LD50 is the amount of a material, given all at once, which causes the death of 50% (one half) of a group of test animals. The LD50 is one way to measure the short-term poisoning potential (acute toxicity) of a material. Nephrotoxins a toxic agent or substance that inhibits, damages or destroys the cells and/or tissues of the kidneys Neurotoxins are toxins that are destructive to nerve tissue (causing neurotoxicity) Oxidizers are solid, liquids or gases that react readily with most organic material or reducing agents with no energy input PPE stands for Personal Protective Equipment. It refers to any equipment worn to minimize exposure to hazards that cause serious workplace injuries and illnesses Pyrophoric substances that ignite instantly upon exposure to oxygen, they can also be water reactive, where heat and hydrogen (a flammable gas) are produced Risk defined as a measure of human injury, environmental damage, or economic loss in terms of both the incident likelihood (probability) and the magnitude of the loss or injury (consequence) Safety Data a document produced in alignment with the UN’s Globally Harmonized Sheet System of Classification and Labelling of Chemicals (GHS) that the manufacturer, importer, or distributor of a chemical product is required to provide to downstream users. An SDS needs to have a specific 16- section format, and the process of creating a properly formatted SDS is known as SDS authoring. Toxic substance that can cause harmful effect to the environment and hazardous to human health if inhaled, ingested or absorbed through the skin 18  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Essential Knowledge INTRODUCTION TO CHEMICAL SAFETY, CHEMICAL HAZARDS, PICTOGRAMS AND CHEMICAL HEALTH RISK Nowadays, a wide range of chemicals are being used in the different field, most especially in the field of research, medicine, product manufacturing and even in our daily living. We utilize chemicals since it enables us to formulate substances important for disease treatment, fertilize plants and provide fuel for transportation. According to the International Labour Organization (ILO) that Chemicals have become part of our life, sustaining many of our activities, preventing and controlling many diseases and increasing agricultural productivity. However, one cannot ignore that many of these chemicals may, especially if not properly used, endanger our health and poison our environment. Moreover, it has been estimated that approximately one thousand new chemicals come onto the market every year, and about 100 000 chemical substances are used on a global scale. With this topic, that talks about chemical safety we can be able to view the physical and health hazards of chemicals, that requires implementation of safety precautions and hazard control that can reduce the risk of exposure. What is chemical safety? It is the application of the best practices for handling chemicals and chemistry processes to minimize risk, whether to a person, facility, or community. It involves understanding the physical, chemical and toxicological hazards of chemicals, (Kemsley, 2013). Chemical safety provides information about the practice of handling chemicals in a safe manner, thus minimizing the hazard to public and personal health. According to the World Health Organization (WHO), chemical safety is achieved by undertaking all activities involving chemicals in such a way as to ensure the safety of human health and the environment. It covers all chemicals, natural and manufactured, and the full range of exposure situations from the natural presence of chemicals in the environment to their extraction or synthesis, industrial production, transport use and disposal. 19  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Chemical safety focuses to the following: Identify the hazard: This involves identifying the chemicals you have in your workplace and the hazards associated with them. Assess the risk: This involves assessing the risk from chemicals or processes in your workplace. Control the exposure: This involves considering the various recognized control measures to eliminate or reduce the risk. Courtesy: Health and Safety Authority CHEMICAL HAZARDS A chemical hazard is a type of occupational hazard caused by exposure to chemicals in the workplace. Chemical hazards will give an idea to the user on what are the things that needs to be observe, what are the preventive measures that needs to be done, and what are the things needed and not needed in order to handle chemicals safely. (Indian Standard (IS) 4209-1987 Code of Safety in Chemical Laboratories.) TYPES OF CHEMICAL HAZARDS Corrosives Corrosives are chemicals which cause burns on the skin, mucous membrane and eyes. Chemical burns are also caused when tissues come in contact with corrosive solids, corrosive liquids dispersed in the air as mists. This kind of chemicals are highly reactive substances it can cause obvious damage to living tissue. Examples of corrosive chemicals a. Sulfuric acid b. Nitric acid, 20  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 c. Potassium hydroxide (caustic potash) d. Sodium hydroxide (caustic soda), e. Bromine and phenol Courtesy: Hazards in Chemical Lab. Oxidizers Oxidizers are solid, liquids or gases that react readily with most organic material or reducing agents with no energy input. Oxidizers are a severe fire hazards. They must be stored away from flammables, since they can start a fire if they come in contact with each other. Thus oxidizing chemicals can cause fire and can burn violently. Examples of oxidizing chemicals a) Hydrogen Peroxide b) Nitric Acid, c) Perchloric Acid, d) Sulphuric Acid e) Chlorates f) Chromates, Courtesy: Hazards in Chemical Lab 21  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Flammable Flammable substance are those gases, liquids and solids that will ignite and continue to burn in air if exposed to a source of ignition. Flammable chemicals are a fire hazard. The lower the flashpoint (the lowest temperature at which a liquid fuel will give off enough vapour to form a momentarily ignitable mixture with air.) of the chemical, the greater the hazard. Examples of flammable chemicals a) Acetone b) Toluene c) Methyl Alcohol Courtesy: Hazards in Chemical Lab Water Reactive Water reactive chemicals are dangerous when wet because they will undergo a chemical reaction with water. This reaction may release a gas that is either flammable or present a toxic health hazard Examples of flammable chemicals a) Sodium b) Lithium c) Potassium Courtesy: Hazards in Chemical Lab 22  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Pyrophorics Pyrophoric chemicals are substances that ignite instantly upon exposure to oxygen, they can also be water reactive, where heat and hydrogen (a flammable gas) are produced. This are liquids, solids and gases that will ignite spontaneously in air at or below 130 degrees Fahrenheit, handling and usage of pyrophoric require fire resistant lab coat, fire resistant hand gloves, safety glasses and face shield. Examples of pyrophoric chemicals a) Butyl Lithium. b) Diisobutylaluminium Hydride Courtesy: Hazards in Chemical Lab Toxic Toxic chemicals are substance that can cause harmful effect to the environment and hazardous to human health if inhaled, ingested or absorbed through the skin. Toxic chemicals produce injurious or lethal effects upon contact with body cells due to their chemical properties. The extent of exposure is determined by the dose, duration and frequency of exposure and the route of exposure. 5 TYPES OF TOXIC CHEMICALS Neurotoxins- the target organ for this type of toxic chemical is the nervous system. Examples: xylene, carbon-hexane, trichloroethylene. Hematotoxins – the target part is the blood. Examples: carbon monoxide, nitrates Hepatotoxins – the target part is the liver. 23  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Examples: chloroform, dinitrobenzene Nephrotoxins – the target part is the kidney. Examples: cadmium, mercury, carbon Dermatotoxins – the target part is the skin. Examples: organic solvents Courtesy: Hazards in Chemical Lab Potentially Explosive Chemicals An explosive chemical is a solid or liquid chemical which is in itself capable by chemical reaction of producing gas at such a temperature and pressure and at such a speed to cause damage to the surroundings. This are chemicals that when subjected to heat, impact, or friction, undergoes rapid chemical change, evolving large volumes of gases which cause sudden increase in pressure. Examples of potentially explosive chemicals: a) Acetylides b) Azides c) Nitrogen triiodide d) Organic nitrates e) Nitro compounds f) Perchlorate salts Courtesy: Hazards in Chemical Lab 24  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 PICTOGRAMS According to the Canadian Centre for Occupational Health and Safety (CCOHS) The Hazard Communication Standard (HCS) requires pictograms on labels to alert users of the chemical hazards to which they may be exposed, each pictogram consist of a symbol on a white background framed within a red border and represent a distinct hazard. There are two classification of pictograms the Health Hazard Pictogram and Physical Hazard Pictogram. CLASSIFICATION OF PICTOGRAMS Health Hazard Pictogram Health hazard Exclamation mark Carcinogen Irritant (skin Mutagenicity and eye) Reproductive Skin Sensitizer Toxicity Acute Toxicity Respiratory Sensitizer Narcotic Effects Target Organ Respiratory Skull and cross bones Toxicity Tract Irritant Corrosion Aspiration Toxicity Acute toxicity Skin (fatal or toxic) Corrosion/Burn Eye Damage Corrosive to Metals Physical Hazard Pictogram Exploding bomb Flame over circle Explosives Oxidizers Self-Reactive Organic Peroxides 25  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Gas cylinder Flame Gases Under Pressure Flammables Pyrophorics Self-Heating Emits Flammable Gas Self-Reactives Environment Aquatic toxicity Courtesy: Hazards in Chemical Lab 26  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 CHEMICAL HEALTH RISK A chemical incident is the unexpected release of a substance that is (potentially) hazardous either to humans, other animals or the environment. Chemical releases arise from technological incidents, impact of natural hazards4, and from conflict and terrorism.5 The International Federation of the Red Cross has estimated that between 1998 and 2007, there were nearly 3 200 technological disasters, including chemical incidents, with approximately 100 000 people killed and nearly 2 million people affected.5 The management of chemical incidents requires a multi- disciplinary and multi-sectoral approach - the health sector may play a supporting or a leadership role at various stages of the management. (WHO Human Health Risk Assessment Toolkit: Chemical Hazards. 2010). The following are the identified chemical health risk, i. FIRE produces injuries through heat and exposure to toxic substances (including combustion products). ii. EXPLOSION produces traumatic (mechanical) injuries through the resulting shockwave (blast), fragments and projectiles. iii. TOXICITY may result when humans come into contact with a chemical released from its containment, be it from storage or transport, or as reaction or combustion products. Toxicity can cause harm by a wide array of toxic mechanisms ranging from chemical burns to asphyxiation and neurotoxicity. iv. MENTAL HEALTH effects are not only determined by exposure to the chemical, fire or explosion but also by “exposure to the event” itself. ROUTES OF ENTRY OF CHEMICALS TO OUR BODY The main routes of entry of the chemicals into the human body are: Inhalation into lungs. Absorption through skin membrane/cuts in the skin. Ingestion via mouth into the gastrointestinal system. 27  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 COMMON CHEMICAL GROUPS THAT CAUSE HEALTH RISKS OR SPECIFIC CHEMICAL HAZARDS Types: Dusts and Fumes Gases Solvents Metals Acids and Bases Pesticides DUST AND FUMES All particles may be harmful; the effect depends on size of particles, amount and nature of substance. Particles less than 10 μm can be breathed deep in the lungs and those less than 2.5 μm is particularly dangerous. Dusts containing crystalline silica or asbestos may cause incurable lung damage leading to cancer, especially in smokers: metal fumes may cause “metal fume fever” (Duffus, J. & Worth, H.,n.d.) GASES Gases such as sulfur oxides, nitrogen oxides, chlorine and ammonia are corrosive and irritating to the lungs and nose (Duffus, J. & Worth, H., n.d.) Phosgene is formed when solvents containing chlorine, such as trichloroethane, trichloroethylene, or carbon tetrachloride come into contact with hot surfaces or flames. Carbon monoxide is an odorless and colorless gas formed by incomplete burning of carbon compounds: Carbon monoxide gradually blocks oxygen supply to the nervous system, making your brain function less effectively before it causes death; it reacts with hemoglobin stopping it carrying oxygen in the blood. 28  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Hydrogen cyanide gas can pass through the skin as well as the lungs and kills by depriving your brain and heart of oxygen; it reacts with the final electron carrier of the cytochrome system to block cell respiration. SOLVENTS Apart from water, most solvents are liquid organic chemicals and many evaporate rapidly at room temperature. Organic solvents are often flammable: organic solvent vapors may be inhaled or the liquid absorbed through the skin. Benzene can cause leukemia, a cancer of the white blood cells Carbon tetrachloride can cause severe liver damage. Carbon disulfide affects the brain and nervous system causing character change and unpredictable behavior. ACIDS AND BASES Acids and bases have corrosive properties. The amount of harm caused by chemical burns from acids and bases depends on the concentration of the substance and the duration of exposure (Retrieved from https://sciencing.com/acids-bases- harmful-6019071.html). Strong Acids Acids with a pH of less than 4 can cause chemical burns. Some common strong acids include hydrochloric, nitric, sulfuric and phosphoric acids. Weak acids such as acetic, citric and carbonic are not corrosive. They can safely be consumed and do not irritate the skin. However, at greater concentrations weak acids can be harmful. Strong Bases Bases with a pH greater than 10 can cause chemical burns. Strong bases include, calcium hydroxide, sodium hydroxide and potassium hydroxide. Some common weak bases are ammonia and sodium bicarbonate. Chemical burns from bases do not cause as much pain as acid burns, but the damage can be more extensive. 29  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 CHEMICAL GROUPS: ITS SOURCES AND ITS EFFECTS ON LIVING ORGANISMS The use of chemicals has increased dramatically due to the economic development in various sectors including industry, agriculture and transport. As a consequence, people are exposed to a large number of chemicals of both natural and man-made origin (World Health Organization). Chemicals come from different sources and also come in different forms. Human exposure to hazardous chemicals can occur at the source or the chemical could move to a place where people can come into contact with it. The chemical getting into our body has had an adverse effect on our health. Thus, creates a greater risk in experiencing different kinds of symptoms and diseases. Health effects depend on the toxicity of a chemical group that entered our body, on the rate of absorption of the body and the response of the body to the chemical (Missouri Department of Health & Senior Services). CHEMICAL GROUP/S THAT CAUSES HEALTH RISKS: METALS Metals are substances with high electrical conductivity, malleability, and luster, which voluntarily lose their electrons to form cations. Metals are found naturally in the earth's crust and their compositions vary among different localities, resulting in spatial variations of surrounding concentrations (Anbalagan, N. et.al., 2014). Metals are well- known for its adverse benefits and uses. But other sources of metal could have a harmful effect on the environment and living organisms. Heavy Metals Heavy metals are generally referred to as those metals which possess a specific density of more than 5 g/cm3 and adversely affect the environment and living organisms. These metals are quintessential to maintain various biochemical and physiological functions in living organisms when in very low concentrations; however they become noxious when they exceed certain threshold concentrations. Heavy metal toxicity has proven to be a major threat and there are several health risks associated with it. The toxic effects of these metals, even though they do not have any biological role, remain present in some or the other form harmful for the human body and its proper functioning. They sometimes act as a pseudo element of the body while at certain times they may even interfere with metabolic processes (Anbalagan, N. et.al., 2014). It is being said that heavy metal exposure continues and is increasing in many parts of the world. Heavy metals are significant environmental pollutants and their 30  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 toxicity is a problem of increasing significance for ecological, evolutionary, nutritional and environmental reasons. Sources of Heavy Metals Various sources of heavy metals include soil erosion, natural weathering of the earth's crust, mining, industrial effluents, urban runoff, sewage discharge, insect or disease control agents applied to crops, and many others. COMMON HEAVY METALS A. Lead Lead is a highly toxic metal whose widespread use has caused extensive environmental contamination and health problems in many parts of the world. Lead is an extremely toxic heavy metal that disturbs various plant physiological processes and unlike other metals, such as zinc, copper and manganese, it does not play any biological functions. Lead metal causes toxicity in living cells by following ionic mechanism and that of oxidative stress. Under the influence of lead in the body system, there will be an imbalance between the production of free radicals and antioxidants to detoxify the reactive intermediates or to repair resulting damage in the body (Anbalagan, N. et.al., 2014). Sources of Lead The sources of lead were gasoline and house paint, which has been extended to lead bullets, plumbing pipes, pewter pitchers, storage batteries, toys and faucets. B. Mercury Mercury is very toxic and exceedingly bio accumulative. Its presence adversely affects the marine environment and hence many studies are directed towards the distribution of mercury in water environment. It is well known as a hazardous metal and its toxicity is a common cause of acute heavy metal poisoning. The brain remains the target organ for mercury, yet it can impair any organ and lead to malfunctioning of nerves, kidneys and muscles. It can cause disruption to the membrane potential and interrupt with intracellular calcium homeostasis. Mercury plays a key role in damaging the tertiary and quaternary protein structure and alters the cellular function by attaching to the selenohydryl and sulfhydryl groups which undergo reaction with methyl mercury and hamper the cellular structure. It also intervenes with the process of transcription and translation resulting in the disappearance of ribosomes and eradication of endoplasmic reticulum and the activity of natural killer cells. 31  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Mercury exists mainly in three forms: metallic elements, inorganic salts and organic compounds, each of which possesses different toxicity and bioavailability. These forms of mercury are present widely in water resources such as lakes, rivers and oceans where they are taken up by the microorganisms and get transformed into methyl mercury within the microorganism, eventually undergoing biomagnification causing significant disturbance to aquatic lives (Anbalagan, N. et.al., 2014). Major Sources of Mercury Pollution Major sources of mercury pollution include anthropogenic activities such as agriculture, municipal waste water discharges, mining, incineration, and discharges of industrial waste water. C. Chromium The most commonl