Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Chapter 1 Learning Goals 1. Describe the Kinetic Molecular Theory and be able to describe how it helps to explain the properties of gases, liquids and solids. 2. Know the common units for temperature, mass, length and volume. 3. Convert from one measure to another using the factor label method and solve problems using dimensional analysis. 4. Express measurements using the correct number of significant figures indicating the uncertain digit. Use significant figures correctly in mathematical operations. 5. Differentiate between accuracy and precision and explain the conditions under which a measuring instrument can be deemed accurate. Explain how random error differs from systematic error. 6. Be able to determine the density of a substance using laboratory techniques or mathematical operations. 7. Diagram a flow chart illustrating the separation of homogeneous and/or heterogeneous mixtures. Be able to identify the mixture type, pure substances, compounds and elements. Identify the physical and chemical changes used in the separation process. AP Chemistry Chapter 2 Study Guide Page 1
Chapter 2 Learning Goals 1. Be able to summarize and recognize applications of the following laws: Conservation of Mass, Law of Definite Proportions, Law of Multiple Proportions, Dalton s Atomic Theory, and Avogadro s Hypothesis. 2. Outline the development of the modern atomic model including the work of Thomson, Millikan, and Rutherford. 3. Identify the number of subatomic particles using information from the nuclear symbol for atoms, ions and isotopes. 4. Define the term atomic mass and explain why a mass spectrometer can be used to determine the atomic mass of an element. Use data from the mass spectrometer to determine the atomic mass. 5. For a given sample of an element be able to determine a) the number of moles b) the number of individual atoms c) the mass of the sample. Be able to explain the significance of using mole measurements in the chemical laboratory. 6. For a given sample of a compound you should be able to determine a) the number of moles of the compound b) the number of moles of individual ions or atoms and c) the molar mass 7. Using the Periodic Chart predict the properties of a substance from its position in the chart. 8. Describe the difference between an ionic and a molecular compound. 9. Identify the information given in a chemical and a structural formula for a molecular compound. Be able to write the formula and name from the sturctural formula. 10. Explain how cations and anions are formed and determine the ionic charge from given data. 11. Describe the difference between the ionic and the covalent bond. Predict the properties of both molecular and ionic compounds 12. Know the name of polyatomic ions. 13. Name type I, II and III binary ionic compounds; compounds composed of polyatomic ions; and common acids. 14. Given the systematic names of compounds, write the correct chemical formulas. 15. Determine the percent by mass of an element in a given compound and the percentage composition of a given compound. Predict the mass of a particular element found in a given sample of a compound. 16. Determine the empirical formula and molecular formula for a given compound from provided data and from the laboratory setting. AP Chemistry Chapter 2 Study Guide Page 2
NOTES CHAPTER 1 SIGNIFICANT FIGURES USE IN THE LAB - use all digits on electronic devices use all marked lines and 1 estimate on instruments with gradations. PROBLEM SOLVING - USE OF SIGNIFICANT FIGURES How many significant figures? 40.150 g 1 m = 1000 mm 4050 ml 4000 km RULES : 1. 2. 3. 4. 5. AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 3
MATHEMATICAL OPERATIONS ADDITION/SUBTRACTION: MULTIPLICATION/DIVISION What is the volume of 14.25 g of alcohol if the density of alcohol is 0.70 g/ml. Express the volume in both milliliters and cubic centimeters. CONVERSIONS - USE DIMENSIONAL ANALYSIS. SHOW ALL UNITS AND CANCEL 10 0 Convert 0.0537 cm to meters base L, g, m to nanometers to kilometers Convert a density of 4.85 g/ cm 3 to kg/l Convert 25.0 cm 3 to m 3 and dl AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 4
The aluminum in a package containing 75.0 ft 2 of kitchen foil weighs approximately 12.0 oz. Aluminum has a density of 2.70 g/cm 3. What is the approximate thickness of the aluminum foil in millimeters? ( 1 oz = 28.4 g) PERCENT PROBLEMS The density of a solution of sulfuric acid is 1.285 g/ cm 3 and it is 38.08 % acid by mass. What volume of the acid solution ( in ml) do you need to supply 125 g of sulfuric acid? ACCURACY AND PRECISION Three student lab groups measured the mass of five aluminum bars, each labeled one mole. Al bar Group A Group B Group C 1 28.01 27.00 26.78 2 28.38 26.90 26.93 3 28.38 25.70 27.00 4 28.67 28.51 26.96 5 28.40 25.41 27.21 What is the mass of 1 mole of aluminum exactly? How would you describe the accuracy and precision of each group s measurements? Propose explanations for the patterns you see in each group s data. Determine the % Error for Group A s Bar 1. AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 5
REVIEW OF ATOMIC STRUCTURE - HISTORY LAVOISIER - Conservation of Mass NOTES CHAPTERS 2 PROUST Law of Definite Composition by Mass DALTON Atomic Theory 1. 2. 3. 4. LAW OF MULTIPLE PROPORTIONS (by atoms) AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 6
THOMSON- MILLIKAN- RUTHERFORD - CHADWICK - AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 7
ISOTOPES AND ATOMIC MASSES ATOMIC MASS IS A RELATIVE SCALE ATOMIC MASS OF AN ATOM ATOMIC MASS OF AN ELEMENT 90.51% # 9.22% 0.27% 19.112 20.994 21.990 amu amu amu MASS SPECTROSCOPY The element europium exists in nature as two isotopes: 151 Eu has a mass of 150.9196 amu and 153 Eu has a mass of 152.9209 amu. The average atomic mass of the element is 151.96 amu. Calculate the relative abundance of the two europium isotopes. AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 8
Nuclear symbols A X Z MOLAR MASS: Mass of one mole of an element What is the mass of 1 carbon atom? If you mass out 2.25 grams of barium nitrate. How many moles of barium nitrate are present? Moles of barium ions? Moles of nitrate ions? numbers of oxygen atoms? ions of nitrate? The density of aluminum is 2.70 g/ cm 3. How many aluminum atoms are in a piece of aluminum foil measuring 0.18 m by 12.0 cm by 0.010 mm.? AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 9
0.25 moles of iron III oxide contain how many grams of iron? AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 10
AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 11
ATOMS form molecules of molecular (covalent) compounds IONS form lattices of ionic compounds. EMPIRICAL FORMULA lowest whole number ration of atoms or ions MOLECULAR FORMULA multiples of empirical formula compounds BINARY COMPOUND POLYATOMIC COMPOUND MOLECULAR COMPOUND IONIC COMPOUND ORGANIC COMPOUND LAW OF DEFINITE COMPOSITION All samples of a compound have the same percent composition by mass Determine the % composition of ammonium sulfide If one heats 1.725 g carbon in a hydrogen atmosphere the resulting compound has a mass of 2.300g. Calculate the empirical formula of the compound. If chromium III oxide is obtained from chromium ore ( 99% pure). how many kilograms of chromium can be purified from 1.0 ton of ore? AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 12
A compound is determined to be 1.2 % H, 24.7 % Ca, 14.8% C and 59.3 % O. What is the empirical formula Nicotine is 74.0% carbon, 8.7 % hydrogen and 17.3 % nitrogen. The molecular mass of nicotine is 162 grams. What is the molecular formula of nicotine? A metal M forms a compund MCl 4. If the compound is found to be composed of 74.75% of chlorine, find the molar mass of M and identify the element. Alum is a hydrated compound KAl(SO 4 ) 2 H 2 O. If one heats 4.74 grams of the hydrate, 2.16 grams of water of hydration is driven off to form the anhydrous spieces. What is the formula of the hydrate? AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 13
A compound is composed of carbon, hydrogen and oxygen. The combustion of 10.68 mg of the compound in air produces 16.01 mg of carbon dioxide and 4.37 mg of water. The molecular mass of the compound is 176.1 g/ mol. Find the empirical and molecular formula of the compound. AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 14
STANDARD CONVERSION FACTORS A. Metric Prefixes (exact definitions unlimited significant figures): Prefix Abbreviation Meaning Factor Mega M 1,000,000 10 6 Kilo k 1,000 10 3 Hecto h 100 10 2 Deka da 10 10 1 Deci d 0.1 10-1 Centi c 0.01 10-2 Milli m 0.001 10-3 Micro µ 0.000,001 10-6 Nano n 0.000,000,001 10-9 1cm 3 = 1 ml 1 dm 3 = 1 L 1 metric ton = 1000 kg B. Base Metric System Units (SI units) Length meter m Mass kilogram g Time second s Energy joule J Amount mole mol C. English System Conversion Factors (unlimited significant figures) 1 ft = 12 in 1 gal = 4 qt 1 lb = 16 oz 1 yd = 3 ft 1 qt = 2 pt 1 ton = 2000 lb 1 mi = 5280 ft 1 qt = 32 fl oz 1 year = 365 days 1 min = 60 s 1 hr = 60 min 1 day = 24 hr D. English-Metric Conversion Factors (inexact limited significant figures) 1 in = 2.54 cm 1 L = 1.06 qt 1 lb = 454 g 1 mi = 1.61 km 1 qt = 0.964 L 1 metric ton = 2200 lb AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 15
SEPERATION TECHNIQUES 1. Direct Separation Definition: A manual separation of mixture parts based on some macroscopic or large scale property. Examples: Separation of oil from water (insolubility of liquids) Separation of yellow wooden balls from red wooden balls (physical appearance) Separation of iron from sulfur (iron is magnetic while sulfur is not) 2. Filtration Definition: A process for separating a solid-liquid mixture by passing it through a barrier with fine pores (openings) such as filter paper. Examples when used: For coarse mixtures of solids in liquids like mud or sand from water (particle size and insolubility of mixture) Will NOT work for separating solutions 3. Evaporation Definition: To convert a liquid part of a liquid-solid mixture. To expel moisture from a solution, as by heating, until dry or concentrated. The process by which a liquid exposed to the atmosphere vaporizes. Examples when used: Liquid-solid solutions like sugar or salt in water (boiling point and vapor pressure or ability to evaporate.) Could work for coarse mixtures of liquids and solids like mud or sand in water but this would be less efficient than filtration because it would take longer to do. 4. Distillation (usually called fractional distillation) Definition: A procedure where a liquid is vaporized under conditions where the evolved vapor is later condensed (cooled) and collected. The separation is due to the differences in boiling points. The process of separating a liquid from a solid by driving the liquid off as a gas or vapor by heating in a retort or still, and condensing the vapor product. The separation is due to the differences in the boiling points. Examples when used: Solutions of gasses such as air Solutions of liquids such as alcohol and water. Solutions of solids and liquids such as salt in water. 5. Crystallization Definition: AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 16
To separate from a solution the solid components as the solution is either evaporated or cooled enough to cause crystals of the less soluble solids to form from the solution. Examples when used: To separate a solid impurity from anther solid (using differences in solubility); dissolve impure potassium nitrate in hot water, cool the water to crystallize the potassium nitrate (now pure) and filter off the pure crystals leaving the more soluble impurity behind. To separate 2 or more solids that vary in their ability to dissolve in a liquid solvent; to separate a mixture of potassium nitrate and sodium chloride by dissolving them in hot water, cooling the solution and filtering off the potassium nitrate crystals which form first because of it slower solubility at lower temperatures. 6. Chromatography Definition: A separation method where the components of a solution are adsorbed at different locations on a solid surface due to different solubilities in a common solvent used to dissolve the substances. A separating of closely related compounds by allowing a solution of them to seep through an adsorbent so that the different compounds become adsorbed in separate colored layers comprising a chromatogram. All based on differences in solubility of the compounds in a chromatography solvent and their differing electrical attractions to the adsorbing solid. Examples when used: A mixture of amino acids from dissolving or digesting a protein molecule. The colored dyes found in ink, chemical indicators or food colorings. The colored pigments found in plant leaves such as chlorophyll, xanthophyll, and anthocyanin. 7. Centrifugation Definition: The use of a centrifuge for separating materials of different densities by spinning them around a center of rotation the substances settle in order of most dense to least dense. Examples when used: Coarse mixtures of solids in a liquids such as mud from water, blood cells from blood serum, a precipitate (insoluble solid) from water. AP Chemistry Chapters 1 & 2 Study Guide Measurements, Atomic History & Moles Page 17