Chapter 1 Methods and Measurement PDF

GENERAL, ORGANIC, AND BIOCHEMISTRY 10TH Edition...

GENERAL, ORGANIC, AND BIOCHEMISTRY 10TH Edition Katherine J. Denniston Joseph J. Topping Danaè R. Quirk Dorr Robert L. Caret Chapter 1 Chemistry: Methods and Measurement ©2020 McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior  1.1 Strategies for Success in Chemistry Science of Learning Chemistry: Repetition is central In physical exercise, repetition is required to build muscle In learning, repetition is required for long-term retention of facts ©2020 McGraw-Hill Education  Study Cycle 1. Preview material prior to class 2. Attend class and be an active participant 3. Review your notes soon after class 4. Study using 3 to 5 short, intense, formatted study sessions 5. Assess what you know well and determine what you need to study ©2020 McGraw-Hill Education  Study Session Format 1. Establish goal for session in first 2 to 5 min 2. Spend 30 to 50 min studying with focus 3. Take a 5 to 10 min break 4. After break, review material 5 min Once a week, review all material you have been studying for the week ©2020 McGraw-Hill Education  1.2 The Discovery Process Chemistry: the study of matter its chemical and physical properties the chemical and physical changes it undergoes As matter undergoes changes, it gains or loses energy Matter - anything that has mass and occupies space Energy - the ability to do work to ©2020 McGraw-Hill Education  Role of Chemistry ©2020 McGraw-Hill Education  The Scientific Method Scientific Method - a systematic approach to the discovery of new information Observation Formulation of a question Pattern recognition Theory development Hypothesis: attempt to explain observation(s) Theory: hypothesis supported by extensive testing Experimentation Data: the individual result of a single measurement Results: the outcome of an experiment Information summarization Scientific law: summary of a large quantity of ©2020 McGraw-Hill Education information  Representation of the Scientific Method ©2020 McGraw-Hill Education  Models in Chemistry Aid in the understanding of a chemical unit or system often based on everyday experience Ball and stick model of methane color coded balls (atoms) sticks (attractive forces holding atoms ©2020 McGraw-Hill Education  1.3 The Classification of Matter Properties - characteristics of matter scientists can use to categorize different types of matter Ways to Categorize matter: 1. By State 2. By Composition ©2020 McGraw-Hill Education  Three States of Matter 1. Gas - particles widely separated, no definite shape or volume solid 2. Liquid - particles closer together, definite volume but no definite shape 3. Solid - particles are very close together, define shape and definite volume ©2020 McGraw-Hill Education  Composition of Matter Pure substance - a substance that has only one component Mixture - a combination of two or more pure substances in which each substance retains its own identity, not undergoing a chemical reaction ©2020 McGraw-Hill Education  Pure Substances Element - a pure substance that cannot be changed into a simpler form of matter by any chemical reaction Compound - a pure substance resulting from the combination of two or more elements in a definite, reproducible way, in a ©2020 McGraw-Hill Education  Mixture Mixture - a combination of two or more pure substances in which each substance retains its own identity Homogeneous - uniform composition, particles well mixed, thoroughly intermingled Heterogeneous – nonuniform composition, ©2020 McGraw-Hill Education  Classes of Matter ©2020 McGraw-Hill Education  Physical Property versus Physical Change Physical property - is observed without changing the composition or identity of a substance Physical change - produces a recognizable difference in the appearance of a substance without causing any change in its composition or identity conversion from one physical state to another ©2020 McGraw-Hill Education  Physical Properties and Physical Change ©2020 McGraw-Hill Education (a) ©moodboard/Glow Images; (b)  Separation by Physical Properties Magnetic iron is separated from other nonmagnetic substances, such as sand. This property is used as a large-scale process in the recycling industry. ©2020 McGraw-Hill Education  Chemical Property versus Chemical Reaction Chemical property - results in a change in composition and can be observed only through a chemical reaction Chemical reaction (chemical change) - a chemical substance is converted in to one or more different substances by rearranging, removing, hydrogen  oxygen water replacing, or adding atoms reactants products ©2020 McGraw-Hill Education  Classification of Properties Classify the following as either a chemical or physical property: a. Color b. Flammability c. Hardness d. Odor e. Taste ©2020 McGraw-Hill Education  Classification of Changes Classify the following as either a chemical or physical change: a. Boiling water becomes steam b. Butter turns rancid c. Burning of wood d. Mountain snow melting in spring e. Decay of leaves in winter ©2020 McGraw-Hill Education  Intensive and Extensive Properties Intensive properties - a property of matter that is independent of the quantity of the substance Color Melting Point Extensive properties - a property of matter that depends on the quantity of the substance Mass ©2020 McGraw-Hill Education  1.4 The Units of Measurement Units - the basic quantity of mass, volume or whatever quantity is being measured A measurement is useless without its units English system - a collection of functionally unrelated units Difficult to convert from one unit to another 1 foot = 12 inches = 0.33 yard = 1/5280 miles Metric System - composed of a set of ©2020 McGraw-Hill Education  Metric System Units 1 Mass - the quantity of matter in an object not synonymous with weight Weight = mass × acceleration due to gravity standard unit is the gram (g) The pound (lb) is the common English unit 1 lb = 454 g Mass must be measured on a balance (not a scale) ©2020 McGraw-Hill Education  Metric System Units 2 Length - the distance between two points standard unit is the meter (m) The yard is the common English unit 1 yd = 0.914 m Volume - the space occupied by an object standard unit is the liter (L) The quart is the common English unit 1 qt = 0.946 L ©2020 McGraw-Hill Education  Metric System Prefixes Basic units are the units of a quantity without any metric prefix Prefix Abbreviati Meaning Decimal Equality with major on Equivalent metric units (g, m, or L are represented by x in each) mega M 106 1,000,000. 1 Mx = 106 x kilo k 103 1,000. 1 kx = 103 x deka da 101 10. 1 dax = 101 x deci d 10−1 0.1 1 dx = 10−1 x centi c 10−2 0.01 1 cx = 10−2 x milli m 10−3 0.001 1 mx = 10−3 x micro μ 10−6 0.000001 1 μx = 10−6 x nano n 10−9 0.000000 1 nx = 10−9 x 001 ©2020 McGraw-Hill Education  Relationship among various volume units Volume  Length width height Volume  1 dm 1 dm 1 dm  3 1 dm 3 1 dm 1 L ©2020 McGraw-Hill Education  1.5 The Numbers of Measurement Information-bearing digits or figures in a number are significant figures The measuring device used determines the number of significant figures in a measurement The degree of uncertainty associated with a measurement is indicated by the number of figures used to represent the information ©2020 McGraw-Hill Education  Significant Figures Example Significant figures - all digits in a number representing data or results that are known with certainty plus one ©2020 McGraw-Hill Education  Recognition of Significant Figures All nonzero digits are significant 7.314 has four significant digits The number of significant digits is independent of the position of the decimal point 73.14 also has four significant digits Zeros located between nonzero digits are significant 60.052 has five significant digits ©2020 McGraw-Hill Education  Use of Zeros in Significant Figures Zeros at the end of a number (trailing zeros) are: Significant if the number contains a decimal point 4.70 has three significant digits Insignificant if the number does not contain a decimal point 100 has one significant digit; 100. has three Zeros to the left of the first nonzero integer are not significant ©2020 McGraw-Hill Education  How many significant figures are in the following? 1. 3.400 2. 3004 3. 300. 4. 0.003040 ©2020 McGraw-Hill Education  Scientific Notation Used to express very large or very small numbers easily and with the correct number of significant figures Represents a number as a power of ten Example: 3 4,300 4.3 1, 000 4.3 10 ©2020 McGraw-Hill Education  Scientific Notation Rules 1 To convert a number greater than 1 to scientific notation, the original decimal point is moved x places to the left, and the resulting number is multiplied by 10x The exponent x is a positive number equal to the number of places the decimal 3 point moved 6200 6.2 10 What if you want to express the above number with three significant figures? 3 6.2 10 ©2020 McGraw-Hill Education  Scientific Notation Rules 2 To convert a number less than 1 to scientific notation, the original decimal point is moved x places to the right, and the resulting number is multiplied by 10−x The exponent x is a negative number equal to the number of places 3 the 0.0062 decimal point 6.2 10 moved ©2020 McGraw-Hill Education  Scientific Notation Example When a number is exceedingly large or small, scientific notation must be used to input the number into a calculator: 0.000000000000000000000006692 g must be entered into calculator as:  24 6.692 10 ©2020 McGraw-Hill Education  Represent the following numbers in scientific notation: 1. 0.00018 2. 3004 3. 300. 4. 0.00304 ©2020 McGraw-Hill Education  Accuracy and Precision Accuracy - the degree of agreement between the true value and the measured value Error - the difference between the true value and our estimation Random Systematic Precision - a measure of the agreement of replicate measurements Deviation – amount of variation present in a set ©2020 McGraw-Hill Education  Exact (Counted) and Inexact Numbers Inexact numbers have uncertainty (degree of doubt in final significant digit) Exact numbers are a consequence of counting A set of counted items (beakers on a shelf) has no uncertainty Exact numbers by definition have an infinite number of significant figures ©2020 McGraw-Hill Education  Rules for Rounding Numbers When the number to be dropped is less than 5, the preceding number is not changed When the number to be dropped is 5 or larger, the preceding number is increased by one4 unit 3.34966 10 Round the following 4 number to 3  3.35 10 significant figures: ©2020 McGraw-Hill Education  Round off each number to three significant figures: 1. 61.40 2. 6.171 3. 0.066494 ©2020 McGraw-Hill Education  Significant Figures in Calculation of Results Rules for Addition and Subtraction The result in a calculation cannot have greater significance than any of the quantities that produced the result Consider: 37.68 liters 6.71862 liters 108.428 liters correct answer 152.83 liters ©2020 McGraw-Hill Education  Report the result of each to the proper number of significant figures: 1. 4.26 + 3.831 2. 8.321 − 2.4 ©2020 McGraw-Hill Education  Adding and Subtracting in Scientific Notation There are two ways to solve the following: 6 5 9.47 10  9.3 10 SOLUTION 1: convert both numbers to standard form and add 0.000009 47 + 0.000093 0.000102 correct 47 answer 1.02 × 10 −4 ©2020 McGraw-Hill Education  Addition Example There are two ways to solve the following: 6 5 9.47 10  9.3 10 SOLUTION 2: change one of the exponents so that both have the same power of 10, then add 9.47 × 10−60.9 changes 47 × to 0.947 × 10−5 10−5 + 9.3 × 10−5 correct 10.2 47 × answer 1.02 × 10 −4 ©2020 McGraw-Hill Education  Rules for Multiplication and Division The answer can be no more precise than the least precise number from which the answer is derived The least precise number is the one with the fewest significant 3 figures (4.2 10 )(15.94) 4 2.96886918 (on calculator) 2.255 10 Which number has the fewest significant figures? 4.2  103 has only 2 The answer is therefore, 3.0 ©2020 McGraw-Hill Education  1.6 Unit Conversion Factor-Label Method (Dimensional Analysis) Uses Conversion Factors to: Convert from one unit to another within the same system Convert units from one system to another ©2020 McGraw-Hill Education  English Unit Conversion - Example To convert from one unit to another you must know the conversion factor, which is the relationship between the two units The Relationship: 1 gal = 4 qt The Conversion Factor: 1 gal 4 qt or 4 qt 1 gal ©2020 McGraw-Hill Education  Using Conversion Factors Convert 12 gallons to quarts The Relationship (English system): 1 gal = 4 qt The Conversion Factor: 1 gal 4 qt or 4 qt 1 gal Data Given: 12 gal Use Conversion Factor with gal in denominator ©2020 McGraw-Hill Education  Using Conversion Factors - Solution Convert 12 gallons to quarts Solution: Write the Data Given Multiply by the Conversion Factor with the unit of the Data Given (gal) in the denominator 4 qt 12 gal  48 qt 1 gal Desired Result ©2020 McGraw-Hill Education  Unit Conversion - Example Convert 360 feet to miles The Relationship (English system): 5280 ft = 1 mi The Conversion Factor: 5280 ft 1 mi or 1 mi 5280 ft Data Given: 360 ft Use Conversion Factor with ft in denominator ©2020 McGraw-Hill Education  Unit Conversion - Solution Convert 360 feet to miles Solution: Write the Data Given Multiply by the Conversion Factor with the unit of the Data Given (ft) in the denominator 1 mi 360 ft  0.068 miles 5280 ft Desired Result ©2020 McGraw-Hill Education  Multistep Conversion - Example Convert 0.0047 kilograms to milligrams The Relationships (metric system): 1 kg = 103 g and 103 mg = 1 g The 103 g Factors: 1 kgConversion 1 mg 10 3 g 3 or and 3 or 10 g 1 kg 10 g 1 mg Data Given: 0.0047 kg 1. Use Conversion Factor with kg in denominator to convert to Initial Data Result in g ©2020 McGraw-Hill Education  Multistep Conversion - Solution Convert 0.0047 kilograms to milligrams 3 10 g 0.0047 kg  4.7 g 1 kg Data Given × Conversion Factor = Initial Data Result 1 mg 3 4.7 g   3 4.7 10 mg 10 g Initial Data Result × Conversion Factor = Desired Result ©2020 McGraw-Hill Education  Multistep Conversions - Alternate Solution Convert 0.0047 kilograms to milligrams Alternatively, solve in a single step: 3 10 g 1 mg 3 0.0047 kg    3 4.7 10 mg 1 kg 10 g Data Given × Conversion Factor × Conversion Factor = Desired Result ©2020 McGraw-Hill Education  Practice Unit Conversions 1. Convert 5.5 inches to millimeters 2. Convert 50.0 milliliters to pints 3. Convert 1.8 in2 to cm2 ©2020 McGraw-Hill Education  1.7 Additional Experimental Quantities Temperature - the degree of “hotness” of an object ©2020 McGraw-Hill Education  Conversions Between Fahrenheit and Celsius T F  32 T C  1.8 T F 1.8 T C  32 1. Convert 75 degrees C to degrees F 2. Convert −10 degrees F to degrees C 1. Answer: 167 2. Answer: −23 degrees F ©2020 McGraw-Hill Education degrees C  Kelvin Temperature Scale The Kelvin (K) scale is another temperature scale It is of particular importance because it is directly related to molecular motion As molecular speed increases, the Kelvin temperature proportionately increases TK T C  273.15 ©2020 McGraw-Hill Education  Energy Energy - the ability to do work kinetic energy - the energy of motion (energy of action) potential energy - the energy of position (stored energy) Energy is also categorized by form: light heat electrical mechanical ©2020 McGraw-Hill Education  Characteristics of Energy Energy cannot be created or destroyed Energy may be converted from one form to another Energy conversion always occurs with less than 100% efficiency All chemical reactions involve either a “gain” or “loss” of energy ©2020 McGraw-Hill Education  Units of Energy Basic Units: calorie or joule 1 calorie (cal) = 4.18 joules (J) kilocalorie (kcal) = food Calorie 1 kcal = 1 Calorie = 1000 calories 1 calorie = amount of heat energy required to increase the temperature of 1 gram of water 1 degree C. ©2020 McGraw-Hill Education  Concentration Concentration: the number or mass of particles of a substance contained in a specified volume Often used to represent the mixtures of different substances Concentration of oxygen in the air Pollen counts Proper dose of an antibiotic ©2020 McGraw-Hill Education  Density and Specific Gravity Density the ratio of mass to volume mass m d  volume V an extensive property use to characterize a substance as each substance has a unique density Units for density include: g/mL g/cm3 g/cc ©2020 McGraw-Hill Education  Density Examples ©2020 McGraw-Hill Education  Densities of Some Common Materials Substance Density (g/mL) Substan Density (g/mL) ce Air 0.00129 (at 0 degrees Mercury 13.6 C) Ammonia 0.000771 (at 0 Methanol 0.792 degrees C) Benzene 0.879 Milk 1.028 to 1.035 Blood 1.060 Oxygen 0.00143 (at 0 degrees C) Bone 1.7 to 2.0 Rubber 0.9 to 1.1 Carbon 0.001963 (at 0 Turpentin 0.87 dioxide degrees C) e Ethanol 0.789 Urine 1.010 to 1.030 Gasoline 0.66 to 0.69 Water 1.000 (at 4 degrees C) Gold 19.3 Water 0.998 (at 20 ©2020 McGraw-Hill Education  Calculating Density A 2.00 cm3 sample of aluminum is found to weigh 5.40 g. Calculate the density in g/cm3 and g/mL. Use the expression: Density (d) = m/V 5.40information Substitute g given 3 into the d expression 3 2.70 g cm 2.00 cm Since 1 cm3 = 1 mL, = 2.70 g/mL ©2020 McGraw-Hill Education  Use Density in Calculation Calculate the volume, in mL, of a liquid that has a density of 1.20 g/mL and a mass of 5.00 g. Density can 1.20beg written as1amL Conversion Factor or 1 mL 1.20 g Multiply the Data Given (g) by the Conversion Factor with the unit g in the denominator 1 mL 5.00 g  4.17 mL 1.20 g ©2020 McGraw-Hill Education  Density Calculations Air has a density of 0.0013 g/mL. What is the mass of 6.0-L sample of air? Calculate the mass in grams of 10.0 mL if mercury (Hg) if the density of Hg is 13.6 g/mL. Calculate the volume in milliliters, of a liquid that has a density of 1.20 g/mL and a mass of 5.00 grams. ©2020 McGraw-Hill Education  Specific Gravity Values of density are often related to a standard Specific gravity - the ratio of the density of the object in question to the density of pure water at 4 degrees C Specific gravity is a unitless term because the 2 units cancel Often the health industry uses  g  specific density of object  gravity to test urine and blood samples mL  specific gravity   g  density of water   mL  ©2020 McGraw-Hill Education