BCHE-111L Chemistry for Engineers PDF

College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City...

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