Chapter 1 - Chemical Foundations PDF

Cover Page Chapter 1 Chemical Foundations Copyright ©2018 Cengage Learning. All Rights Reserved. Chapter 1 Table of Contents (1.1)of contents Table Chemist...

Cover Page Chapter 1 Chemical Foundations Copyright ©2018 Cengage Learning. All Rights Reserved. Chapter 1 Table of Contents (1.1)of contents Table Chemistry: An overview (1.2) The scientific method (1.3) Units of measurement - (1.4) Uncertainty in measurement (1.5) Significant figures and calculations (1.6) Learning to solve problems systematically (1.7) Dimensional analysis (1.8) Temperature (1.9) Density (1.10) Classification of matter Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.1 Chemistry: An Overview Chemistry - Introduction Humans have believed that matter is composed of atoms > smallest particle - retain property of element Loading… Recent development - Individual atoms can be viewed by using a scanning tunneling microscope (STM) test available equipment to look at atom o Copyright ©2018 Cengage Learning. All Rights Reserved. 3 Section 1.1 Chemistry: An Overview combine & produce things new - elements can Configuration of Atoms Properties of a substance can be determined by the way in which atoms are organized in that diversity nature substance combinations make in Example - Water is composed two atoms, Hz 02 hydrogen and oxygen H20 Two hydrogen atoms and one oxygen atom are bound together to form the water molecule Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.1 Chemistry: An Overview Configuration of Atoms (continued 1) When an electric current is passed through water, it decomposes to hydrogen and oxygen Loading… Both chemical elements exist naturally as diatomic (two- atom) molecules Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.1 Chemistry: An Overview Configuration of Atoms (continued 2) Decomposition of water to its component elements can be represented in the following manner: 2H20 > - 2H2 + O2 Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.2 The Scientific Method Science Framework for gaining and organizing knowledge Procedure for processing and understanding certain types of information used for scientific study > - Scientific method Lies at the center of scientific inquiry Varies based on the nature of a specific problem and the particular investigator involved Copyright ©2018 Cengage Learning. All Rights Reserved. 7 Section 1.2 The Scientific Method Figure 1.3 - Fundamental Steps of the Scientific Method > - why ? A question for question possible explanation red will fall > - ex : anything can be wrong dis limitsscope slow F too many theories may progress "must be true" need to start from O : don't headstart a gives Copyright ©2018 Cengage Learning. All Rights Reserved. 8  Section 1.2 The Scientific Method Steps in the Scientific Method. Make observations Qualitative observations do not involve numbers Quantitative observations (measurements) involve both a number and a unit. Formulate a hypothesis Hypothesis: Possible explanation for an observation Copyright ©2018 Cengage Learning. All Rights Reserved. 9  Section 1.2 The Scientific Method Steps in the Scientific Method (continued). Perform experiments to test the hypothesis Gather new information that would enable the scientist to ascertain the validity of the hypothesis Experiments always produce new observations that bring the process back to the beginning again Copyright ©2018 Cengage Learning. All Rights Reserved. 10 Section 1.2 The Scientific Method Scientific Models Theory (model): Set of tested hypotheses that gives an overall explanation of a natural phenomenon Loading… Explanation of why nature behaves in a certain way Constantly refined or replaced as more information becomes available Explains observed natural behavior in terms of human experiences Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.2 The Scientific Method Scientific Models (continued) Observations Events that are witnessed and can be recorded Natural law: A summary of observed (measurable) WRONG did not prove NOT behavior simply stating for modification - - no room it TRUE - Example - Law of conservation of mass, which states that the total mass of materials is unaffected by a chemical theories than laws change in those materials (stay same) * more set of experiments theory-proven by a room for modification Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.2 The Scientific Method Law versus Theory Law Theory Statement on generally observed behavior Human inventions Summarizes what happens Attempts to explain why something happens Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.2 The Scientific Method Science: Drawbacks Focusing on a theory may limit one’s ability to see alternative explanations Scientists are humans, and humans have prejudices Science is affected by profit motives, budgets, fads, wars, and religious beliefs Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.3 Units of Measurement Measurement Consists of two essential parts, a number and a scale (unit) - must use correct units Standard systems of units English system - Used in the United States Metric system metric & based SI on SI system (International System) Based on the metric system and units derived from the metric system USED scientific work internationally in Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.3 Units of Measurement Table 1.1 - Fundamental SI Units US... intern metric engl (g) (1b) gram pound (m) (Yk) meter yard S S be can't > 0C of - - & L A A measure of Kinetic mol mol of energy ed cd object Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.3 Units of Measurement uppercase = left Table 1.2 - Prefixes Used in the SI System smaller - bigger iga egao ecienti icro. 6. M KHDBDC.. M M n P...... ang "G mc ↳bae , i mass gram (9) meter (m) length liter (1) Volume memory byte ex : Im = 100 Co M BDC oo 2 12 M = km KH DBDC M I decit 25m = 2000 mm no Copyright ©2018 Cengage Learning. All Rights Reserved. placeend Section 1.3 Units of Measurement Table 1.3 - Some Examples of Commonly Used Units Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.3 Units of Measurement Figure 1.5 - Measurement of Volume E L V = L. W. H I R v= πr2H M = Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.3 Units of Measurement Figure 1.6 - Common Types of Laboratory Equipment Used to Measure Liquid Volume - O - - 250 - - Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.3 Units of Measurement Mass and Weight can use balance (weigh - Mass: Measure of the resistance of an object to a heavy how or O change in its state of motion move south is > I - light (my mass is... 16) Measured by the force necessary to give an object a certain acceleration Weight: Force exerted by gravity on an object Varies with the strength of the gravitational field ↓ gravity Gravitational pull on the O object diff I gravity : Copyright ©2018 Cengage Learning. All Rights Reserved. 21  need certain & uncertain ↓ 1 0. * - con LI O I 2 3 - ~ 1 3. 1. 4 1. 3 uncertain - Certain * we know the 1 is for sure are not sure abt the 2nd # * we Section 1.4 Uncertainty in Measurement Certain and Uncertain Digits Certain digits Numbers that remain the same regardless of who measures them Uncertain digits Digits that must be estimated and therefore vary While reporting a measurement, record all certain digits plus the first uncertain digit Copyright ©2018 Cengage Learning. All Rights Reserved. 22 Section 1.4 Uncertainty in Measurement Measurement of Volume Using a Buret Volume is read at the bottom of the liquid curve, which is called the 20 meniscus Meniscus of the liquid occurs at about 20.15 mL Certain digits - 20.1 - Uncertain digit - 20.15 forseelted Copyright ©2018 Cengage Learning. All Rights Reserved. 23 Section 1.4 Uncertainty in Measurement Uncertainty A measurement always has some degree of uncertainty Uncertainty of a measurement depends on the precision of the measuring device Significant figures: Numbers in which the certain digits and the first uncertain digit are recorded Uncertainty in the last number is always assumed to be them thru ±1 unless otherwise indicated measured #'s - get a device exact #'s - not thiu device Copyright ©2018 Cengage Learning. All Rights Reserved. 24 Section 1.4 Uncertainty in Measurement Precision and Accuracy Accuracy: Agreement of a particular value with the true value ⑳ value => true value Accurate Precision: Degree of agreement among several measurements of the same quantity precise Represents the reproducibility of a given type of measurement Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.4 Uncertainty in Measurement Figure 1.8 - The Results of Several Dart Throws Show the Difference between Precise and Accurate Copyright ©2018 Cengage Learning. All Rights Reserved.  True density 2 80 =. ② 2 4 ③ 2 2 S. 7 ① 2 4.. 2 9. 3 9 23.. 2.. 2 5. ACCURATE NEITHER & PRECISE PRECISE Section 1.4 Uncertainty in Measurement Types of Errors from user no Precision > - no consistency no accuracy Random error (intermediate error) Measurement has an equal probability of being low or high ↑↓ ↑ Occurs in estimating the value of the last digit of a measurement - > from instrument Systematic error (determinate error) Occurs in the same direction each time 9494 or Hutt high Either always high or always low accuracy low precision Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.4 Uncertainty in Measurement An Illustration of the Types of Errors Large random errors Small random errors Small random errors no a and a large systematic and no systematic error error no p but precise wrong Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.4 Uncertainty in Measurement Join In (2) The glassware shown below is called a buret The buret is filled to the zero mark (at the top) with a Loading… solution, and the solution is transferred to a beaker What volume of transferred solution should be reported? 20 mL ↓ for sure 22 mL 22- T tenth is uncertain & 22.0 mL - 22.00 mL 25 mL Copyright ©2018 Cengage Learning. All Rights Reserved.  Section 1.5 Significant Figures and Calculations Rules for Counting Significant Figures. Nonzero integers 235 : 3 sigfigs Always count as significant figures. Zeros - There are three classes of zeros Leading zeros Captive zeros Trailing zeros Copyright ©2018 Cengage Learning. All Rights Reserved. 30  Section 1.5 Significant Figures and Calculations Rules for Counting Significant Figures (continued). Exact numbers infinite sig figs Determined by counting and not by using a measuring device Assumed to have an infinite number of significant figures kg 1 2 2 lbs Can arise from definitions =.. Pencil (infinite 2 Sigligs) # of Example - 2 in 2πr money : infinite ANYTHING COUNTED infinite = Sigfigs Copyright ©2018 Cengage Learning. All Rights Reserved. 31 Section 1.5 Significant Figures and Calculations Counting Significant Figures (Sig. Figs.): Classes of Zeroes Leading zeros Zeros that precede all the nonzero digits Do not count as sig. figs. Example - 0.0025 & has only two sig. figs. - 4 Captive zeros don'ent des dec Zeros between nonzero digits does't or no matter Always count as sig. figs. Example - 1.008 has four sig. figs. 205 - valid BETWEEN · 3 sig figs Copyright ©2018 Cengage Learning. All Rights Reserved. 32 Section 1.5 Significant Figures and Calculations Counting Significant Figures (Sig. Figs.): Classes of Zeroes (continued) Trailing zeros (end of #) Zeros at the right end of the number Significant only if the number contains a decimal point Examples -100 has only one sig fig whereas 1.00×102 has three sig.- figs. Probably not need (sig) (4) measured > - (1) decimal 4 000 g 10. Miles (general 4000g (not sig) (1) 10 0. Miles (3) r this was measured Copyright ©2018 Cengage Learning. All Rights Reserved. 33 Section 1.5 Significant Figures and Calculations Exponential Notation Advantages Number of significant figures can be easily indicated Fewer zeros are required to write a very large or very small number 0000060 Example. 0.000060 was is much more conveniently represented as focus 6.0 × 10–5 ignore exp. on & Number has two significant figures Copyright ©2018 Cengage Learning. All Rights Reserved. 34 Section 1.5 Significant Figures and Calculations Rules for Significant Figures in Mathematical Operations final needs * only answer Multiplication or division correctsigigig gene Number of significant figures in the result is the same as the number in the least precise measurement used in the calculation 25x5 = 125 + 100 ↑ - 15x5 56x1 4 : 6 38- & = 754....Y 6 1 higSig sig ↑ so 25 x 50. = 125 + 130 lowest Sig fig is Limiting term has two Two significant 25 0. x 5 00 = 125-. 1 answer must significant figures figures have 1 sigfig Product should have only two significant figures Copyright ©2018 Cengage Learning. All Rights Reserved. 35 Section 1.5 Significant Figures and Calculations Rules for Significant Figures in Mathematical Operations (continued) Addition or subtraction Result has the same number of decimal places as the least precise measurement used in the calculation Example 12. Il 18. 0 Limiting term has one decimal place 1 235. 1. 0 13 · 04 -5- 13 4. 31. 123 - 31. corrected One decimal place Copyright ©2018 Cengage Learning. All Rights Reserved. 36 Section 1.5 Significant Figures and Calculations Interactive Example 1.4 - Significant Figures in Mathematical Operations Carry out the following mathematical operations, and give each result with the correct number of significant figures 1.05 × 10–3 ÷ 6.135 4 = 1 71. x 18 21 – 13.8 7 = stigs aside places Copyright ©2018 Cengage Learning. All Rights Reserved.  Section 1.5 Significant Figures and Calculations Interactive Example 1.4 - Solution The result is 1.71×10–4, which has three significant figures because the term with the least precision (1.05×10–3) has three significant figures. The result is 7 with no decimal point because the number with the least number of decimal places (21) has none Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.7 Dimensional Analysis Dimensional Analysis (Unit Factor Method) Helps convert a given result from one system of units to another rid of unit - constantly getting a 25m 27 - = y guyd = 27. 33d Copyright ©2018 Cengage Learning. All Rights Reserved. 39 Section 1.7 Dimensional Analysis Problem-Solving Strategy - Converting from One Unit to Another Use the equivalence statement that relates the two units Derive the appropriate unit factor by looking at the direction of the required change to cancel the unwanted units Multiply the quantity to be converted by the unit factor to give the quantity with the desired units Copyright ©2018 Cengage Learning. All Rights Reserved. 40 Section 1.7 Dimensional Analysis Interactive Example 1.6 - Unit Conversions II You want to order a bicycle with a 25.5-in frame, but the sizes in the catalog are given only in centimeters What size should you order? Since we want to convert from inches to centimeters, we need the equivalence statement 2.54 cm = 1 in &. Sin) 2 SCM = 64. Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.7 Dimensional Analysis Interactive Example 1.7 - Unit Conversions III & A student has entered a 10.0-km run sameis How long is the run in miles? To proceed in this way, we need the following equivalence statements: mi L 6 22 Miss 1 km = 1000 m =. 1 m = 1.094 yd 1760 yd = 1 mi Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.7 Dimensional Analysis Interactive Example 1.7 - Solution (continued 2) To make sure the process is clear, we will proceed step by step Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.7 Dimensional Analysis Interactive Example 1.9 - Unit Conversions V A Japanese car is advertised as having a gas mileage of 15 km/L Convert this rating to miles per gallon x3n a Copyright ©2018 Cengage Learning. All Rights Reserved.  2 in 1 ex - miles.- 33miles m use() in deis = 16 m/S Section 1.8 Temperature Systems for Measuring Temperature Celsius scale and Kelvin scale are used in the physical sciences Size of the temperature unit (the degree) is the same Temperature in Celsius units is designated °C, and temperature in Kelvin scale is symbolized by the letter K Fahrenheit scale is used in the engineering sciences Copyright ©2018 Cengage Learning. All Rights Reserved. 45 Section 1.8 Temperature Figure 1.10 - Normal body temperature on the Fahrenheit, Celsius, and Kelvin scales OF = 1. 8% + 32 k = 0 + 273 Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.8 Temperature Kelvin and Celsius Scales Differ in their zero points Conversion between the scales requires an adjustment for the different zero points Copyright ©2018 Cengage Learning. All Rights Reserved. 47 Section 1.8 Temperature Fahrenheit and Celsius Scales: Different Zero Points Converting from Fahrenheit to Celsius TF - Temperature on the Fahrenheit scale TC - Temperature on the Celsius scale Copyright ©2018 Cengage Learning. All Rights Reserved. 48 Section 1.8 Temperature Example 1.12 - Temperature Conversions II One interesting feature of the Celsius and Fahrenheit scales is thatS –40°C and –40°F represent the same temperature Verify that this is true F = 1. 8) + 32 Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.8 Temperature Interactive Example 1.13 - Temperature Conversions III Liquid nitrogen, which is often used as a coolant for low-temperature experiments, has a boiling point of 77 K - What is this temperature on the - Fahrenheit scale? - k = C +273 273 77 = C + 7 = 1. 8C + 32 C = -196 f F = 1. 8 ( 196) + 32 * -87 Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.8 Temperature Interactive Example 1.13 - Solution Where are we going? To convert 77 K to the Fahrenheit scale What do we know? The relationship between the Kelvin and Fahrenheit scales How do we get there? We will first convert 77 K to the Celsius scale TC = TK – 273.15 = 77 – 273.15 = – 196°C Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.8 Temperature Interactive Example 1.13 - Solution (continued) Now convert to the Fahrenheit scale Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.8 Temperature Exercise Convert the following Celsius temperatures to Kelvin and to Fahrenheit degrees Temperature of someone with a fever, 39.2°C 312.4 K; 102.6°F Cold wintery day, –25°C 248 K; –13°F Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.8 Temperature Exercise (continued) Convert the following Celsius temperatures to Kelvin and to Fahrenheit degrees Lowest possible temperature, –273°C 0 K; –459°F Melting-point temperature of sodium chloride, 801°C 1074 K; 1473.8°F Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.9 X Density Density as one M Density= - ↓ mass = grams volume = ml/cm3 1Cm3 = 1 ML Property of matter that is used as an identification tag for substances Density of a liquid can be determined easily by weighing an accurately known volume of liquid Copyright ©2018 Cengage Learning. All Rights Reserved. 55 Section 1.9 Density Interactive Example 1.14 - Determining Density A chemist, trying to identify an unknown liquid, finds that 25.00 Faume cm3 of the substance has a mass of 19.625 g at 20°C - ⑪ mass Which of these compounds is the most likely to be the unknown liquid? D = 125. 1850 > ↑ figs - sig Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.9 Density Interactive Example 1.14 - Solution (continued) Density can be determined by using its definition This density corresponds exactly to that of isopropyl alcohol, which therefore most likely is the unknown liquid However, note that the density of ethanol is also very close To be sure that the compound is isopropyl alcohol, we should run several more density experiments Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.9 Density Table 1.5 - Densities of Various Common Substances* at 20°C 1g/cm3 memorize Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.9 Density Join In (10) too dense , A 25 g cylinder of iron (d = 7.87g/mL) and a 1.0 gram pellet of copper (d = 8.96 g/mL) are placed in 500 mL of water (d = 0.9982 g/mL) than will float - 1 less Predict whether each will float or sink in water , Iron will float, and copper will sink less dense float = must be less dense than water Iron will sink, and copper will float to float ! Iron and copper will sink Iron and copper will float More information is needed Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.10 Classification of Matter # Matter Anything that occupies space and has mass Has many levels of organization and is complex Exists in three states Carrangement Solid Liquid Gas Copyright ©2018 Cengage Learning. All Rights Reserved. 60 Section 1.10 Classification of Matter Properties of a Solid - Rigid Fixed volume and shape : Particles very Slightly compressible close hold on to , each other Solid: The water molecules are locked into rigid positions and are close together Copyright ©2018 Cengage Learning. All Rights Reserved. 61 Section 1.10 Classification of Matter Properties of a Liquid Definite volume No specific shape & Assumes the shape of its 8 & & O container Slightly compressible Liquid: The water molecules are still close together but can move around to some extent Copyright ©2018 Cengage Learning. All Rights Reserved. 62 Section 1.10 Classification of Matter Properties of a Gas No fixed volume or shape Takes on the shape and volume of its container Highly compressible Relatively easy to decrease the volume of a gas Gas: The water molecules are far apart and move randomly Copyright ©2018 Cengage Learning. All Rights Reserved. 63 Section 1.10 Classification of Matter element Pure > - compound Mixtures [ Y Matter Mixture Have variable composition e Classification > - Homogeneous mixture: Has visibly indistinguishable parts and is often called a solution ⑭ > - Heterogeneous mixture: Has visibly distinguishable parts ↳ Pizza No uniformita Can be separated into pure substances, which have constant compositions, by physical methods elements compounds H20 NaCl , Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.10 Classification of Matter Physical Change > - composition does NOT CHANGE (cut paper boil , water) Chemical Change -> change composition (burn paper) Change in the form of a substance No change in the chemical composition of the substance Example Boiling or freezing of water Used to separate a mixture into pure compounds Will not break compounds into elements Copyright ©2018 Cengage Learning. All Rights Reserved. 65 Section 1.10 Classification of Matter Methods for Separating Components in a Mixture difference in boiling point difference in size Distillation Filtration Separation based on boiling separation based on size Point of components involved ALWAYS need to use one * DONT difference in affinity ↑ ex) separating pencils advanced Chromatography based on affinity of compound Copyright ©2018 Cengage Learning. All Rights Reserved. 66 Section 1.10 Classification of Matter Distillation Depends on the differences in the volatility of the components One-stage distillation process involves heating the mixture in a distillation device Most volatile component vaporizes at the lowest temperature Vapor is passed through a condenser, where it condenses back into its liquid state Copyright ©2018 Cengage Learning. All Rights Reserved. 67 Section 1.10 Classification of Matter Figure 1.12 - Simple Laboratory Distillation Apparatus water with with - 9 et water her boiling S lower boiling point hig stays point Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.10 Classification of Matter Filtration Used when a mixture consists of a solid and a liquid Mixture is poured onto a mesh, such as filter paper, which passes the liquid and leaves the solid behind Copyright ©2018 Cengage Learning. All Rights Reserved. 69 Section 1.10 Classification of Matter Chromatography COLOR General name applied to a series of methods that use a system with two states (phases) of matter Mobile phase - Liquid or gas Stationary phase - Solid Separation occurs because the components of the mixture have different affinities for the two phases They move through the system at different rates Copyright ©2018 Cengage Learning. All Rights Reserved. 70 Section 1.10 Classification of Matter Chromatography (continued) Component with a high affinity for the mobile phase will quickly go through the chromatographic system as compared to one with a high affinity for the solid phase Paper chromatography: Uses a strip of porous paper for the stationary phase Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.10 Classification of Matter Figure 1.13 - Paper Chromatography of Ink lower affinity no travel Paper - not Sta moving attracted to ~ mobile = more move liquid moving re Icohol is -canalcohol A mobile sh phs A dot of the mixture to be separated is placed The paper acts as a wick to at one end of a sheet of porous paper draw up the liquid Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.10 Classification of Matter Pure Substances Either compounds or free elements Compound: Substance with a constant composition that can be broken down into its elements via chemical processes atoms of different elements combine together H2O Given substance becomes a new substance or substances with different properties and different composition Element: Substance that cannot be broken down into simpler substances by physical or chemical means Gold Copper , Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.10 Classification of Matter Figure 1.14 - The Organization of Matter 2 elements = compound 2 compounds : mixture ex = Apple & not same (solutions) & composition same composition smallestmakes-molecule unit = stom ex : Vinegar Copyright ©2018 Cengage Learning. All Rights Reserved. 74 Section 1.10 Classification of Matter Join In (11) A solution is also a: heterogeneous mixture Thomogeneous mixture compound distilled mixture pure mixture Copyright ©2018 Cengage Learning. All Rights Reserved. Section 1.10 Classification of Matter Join In (11) A solution is also a: heterogeneous mixture homogeneous mixture compound distilled mixture pure mixture Copyright ©2018 Cengage Learning. All Rights Reserved.