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ANSWER KEY
Chemistry CPA Final Exam Study Guide 1
Chemistry CPA Final Exam Study Guide Final Exam Date: Wednesday, June 17, 2015
Exam Time: 10:15 – 12:00 pm
Topic List Chemical Reactions
Parts of a reaction
Identify the types of reactions
Balance
Write the formula equation if you are given a word equation Mole
Molar Mass
Convert moles-grams and grams-moles
Percent Composition
Stoichiometry
Limiting Reactant
Percent Yield Solutions
Solubility Curves
Molarity Gas Laws and KMT
Kinetic Molecular Theory
Heating/Cooling Curves
Boyle
Charles’
Gay-Lussac
Ideal
Acid/Base
Properties
Calculate pH and pOH and find [H+] and [OH-]
Exam Structure
o Part 1 = 80 points: Multiple choice questions o Part 2 = 20 points: Open-Ended/Free Response
ANSWER KEY
Chemistry CPA Final Exam Study Guide 2
You will be given the following formula sheet and a periodic table.
Mole Conversion Given unit x _____________ Given unit Percent Composition = Mass of element x 100 Molar mass Percent yield = actual x 100 theoretical Gas laws Temperature in Kelvin = °C + 273 P1V1=P2V2 T1V2 = T2V1 T1P2 = T2P1
PV = nRT, where R = 0.0821𝐿∙𝑎𝑡𝑚
𝐾∙𝑚𝑜𝑙
Molarity Acids & Bases pH + pOH = 14
Desired unit
moles
M L
ANSWER KEY
Chemistry CPA Final Exam Study Guide 3
Unit 5: Chemical Reactions
1. What does the law of conservation of mass state? matter is neither
created nor destroyed.
2. Why is it necessary to balance a chemical equation? number of atoms on each side of the equation must be equal.
3. What is the difference between a word equation and a chemical equation? Give an example of each. word equation uses chemical names, chemical equation uses chemical formulas and symbols.
Complete the chart
Symbol Explanation
+ Used to separate two reactants or two products
Yields, separates reactants and products
(s), (l), (g) States of matter; Fe (s)
(aq) Aqueous solution – dissolved in water
ANSWER KEY
Chemistry CPA Final Exam Study Guide 4
4. Identify the type of reaction and balance the reaction.
A) __2__ NaBr + ____ Ca(OH)2 ___ CaBr2 + __2__ NaOH
Type of reaction: _double replacement_________________
B) ___2_ NH3+ ____ H2SO4 ____ (NH4)2SO4
Type of reaction: ___synthesis__________________
C) __2__ C5H9O + __15__ O2 __10 CO2 + _12___ H2O
Type of reaction: combustion_____________________
D) __3__ Pb + ___2_ H3PO4 ___3_ H2 + ____ Pb3(PO4)2
Type of reaction: ___single replacement____________
E) ____ Li3N + ____ NH4NO3 ___ LiNO3 + ___ (NH4)3N
Type of reaction: _____double replacement________
F) __2__ HBr ____H2 + ____Br2
Type of reaction: ____decomposition_________________
ANSWER KEY
Chemistry CPA Final Exam Study Guide 5
5. Balance the reaction: Ag + HNO3 AgNO3 + H2O + NO2
A. 1:1:1:1:1
B. 2:2:2:2:1
C. 2:1:2:2:2
D. 1:2:1:1:1
E. none
6. Given the following word equations, right a formula equation. Then
identify the type of reaction:
A. Sodium metal and chlorine gas react to form sodium chloride
crystals
2 Na(s) + Cl(2) 2 NaCl (s)
B. propane gas and oxygen gas react to form carbon dioxide, water
vapor, and energy.
C3H8(g) + 5 O2(g) 3 CO2 + 4 H2O + energy
C. zinc metal reacts with hydrochloric acid to form zinc chloride
solution and hydrogen gas.
Zn (s) + 2 HCl ZnCl2 + H2 (g)
Lab Questions: Know/be able to do:
Know the signs of a chemical reaction
Know the five classifications of a chemical reaction
Know the activity of metals
ANSWER KEY
Chemistry CPA Final Exam Study Guide 6
Unit 6: Moles
Match each item with the correct statement below. a. particle b. mole c. Avogadro's number 6.02 x 1023 d. percent composition
7. __C____ the number of particles of a substance present in 1 mole of that substance
8. __A____A term to describe an atom, ion, or a molecule
9. ___B___the SI unit used to measure amount of substance
10. ___D____the percent by mass of each element in a compound Molar Mass (use your periodic table)
11. What is the molar mass of AuCl3?
303.32 g
12. What is the molar mass of (NH4)2CO3
96.11 g
13. What is the molar mass of barium? 137.33 g
ANSWER KEY
Chemistry CPA Final Exam Study Guide 7
Moles and Mass (use the molar mass to convert to moles or grams)
14. What is the mass in grams of 5.90 moles of C8H18
674.13 g
15. What is the mass in grams of 9.32 moles of He?
37.28 g
16. What is the number of moles in 432 g Ba(NO3)2?
1.65 mol
17. What is the number of moles of beryllium in 36 g of Be?
4.0 mol Percent Composition (use the molar mass to calculate the percent of the element)
18. What is the percent composition of chromium in BaCrO ?
54.2%
19. What is the percent of carbon in acetone, C H O?
62.0%
ANSWER KEY
Chemistry CPA Final Exam Study Guide 8
Stoichiometry
MgCl2 + 2 NaOH Mg(OH)2 + 2 NaCl
20. Balance the above reaction.
21. What is the mole ratio of MgCl2 to NaOH? 1:2
22. Identify the limiting reactant if 2 mole of MgCl2 and 2 mole of NaOH are
used in a reaction.
NaOH is limiting reactant
2 Li + 2 H(OH) 2 LiOH + H2
23. Balance the above reaction.
24. What is the mole ratio of Li to water? 2:2
25. Identify the limiting reactant if 2 mole Li and 2 mole of water are used in a reaction.
no limiting reactant.
Lab Questions – Know/be able to do:
If you are given grams from lab data, convert to moles
How to determine the mole ratio from lab data (Moles of Fe and Cu
lab)
Predict the products of a single-replacement reaction:
o Mg + HCl ________ + _________ ?
ANSWER KEY
Chemistry CPA Final Exam Study Guide 9
Unit 7: Solution Chemistry
26. Given grams how do you solve for moles? Example: convert 90 grams of
water to moles. divide the given by the molar mass:
90 g / 18 g = 5 mol
27. Molarity is equal to __. a. Grams of solute / moles of solute b. Volume of solution x moles of solute c. Moles of solute / liters of solution d. Volume of solution / grams of solute
28. What mass of methanol, CH3OH, must be dissolved to make 1.50 L of a
0.675M solution? SHOW YOUR WORK!!!!
1. Find mol first: 0.675x1.50 = 1.01 mol 2. then convert to gramsmol = 1.01 mol x 32.05 g = 32.37 g
29. What is the molarity of a solution of HNO3 that contains 250 grams HNO3 in 3 L of solution? Convert grams to moles first.
1. Convert grams moles: 250 g/63.02 g = 4.0 mol
2. solve for M: 4.0 mol/3 L = 1.3 M
30. What volume of 18.0 M H2SO4 is needed to contain 200 g H2SO4? Convert grams to moles first.
1. Convert grams moles200 g/98.08 g = 2.03 mol
2. Solve for V= 2.03/18.0 = 0.11 L
31. How many moles of CaCl2 are required to prepare 2.00 liters of 0.700 M CaCl2?
1.4 mol
ANSWER KEY
Chemistry CPA Final Exam Study Guide 10
32. How many grams of NaI would be used to produce a 2.0 M solution with a
volume of 1.0L? Solve for moles and convert your answer to grams. 1. Find moles: 2.0x1.0 = 2.0 2. Convert moles grams: 2.0 x 149.89 = 299.78 g
ANSWER KEY
Chemistry CPA Final Exam Study Guide 11
Use this solubility curve to answer the next set of questions (#33- 37) on the following page:
ANSWER KEY
Chemistry CPA Final Exam Study Guide 12
33. If there are 100 grams of KNO3 dissolved in 100 g of water at 70oC, the
solution is __.
a. saturated
b. unsaturated
c. supersaturated
34. If there are 10 grams of NaCl dissolved in 100 g of water at 30oC, the
solution is __.
a. saturated
b. unsaturated
c. supersaturated
35. If there are 70 grams of KBr dissolved in 100 g of water at 20oC, the
solution is __.
a. saturated
b. unsaturated
c. supersaturated
36. If there are 120 grams of NaClO3 dissolved in 100 g of water at 60oC, the
solution is __.
a. saturated
b. unsaturated
c. supersaturated
37. If there are 190 grams of KNO3 dissolved in 100 g of water at 70oC, the
solution is __.
a. saturated
b. unsaturated
c. supersaturated
ANSWER KEY
Chemistry CPA Final Exam Study Guide 13
Lab Questions: Know/be able to do:
What “like dissolves like” means
Polar dissolves polar and nonpolar dissolves nonpolar
polar and nonpolar do not dissolve
water is a polar molecule and makes hydrogen bonds
ANSWER KEY
Chemistry CPA Final Exam Study Guide 14
Unit 8: Gas Laws and KMT
Kinetic Molecular Theory and Heating Curves
38. What is the kinetic molecular theory? Gas particles are always in
constant, random motion. The higher the temperature, the higher the
kinetic energy. Gas particles collide with one another in perfectly
elastic collisions. As temp and KE increase, so do collisions, which
raises the pressure within a gas.
39. How are temperature and kinetic energy related?
When Temperature increases, so does KE and vv.
40. When a substance is in a single state of matter and the temperature is
increasing, there will be an increase in the (kinetic energy/potential
energy) of the particles.
41. When a substance is undergoing a phase change and the temperature is
not changing, there will be an increase in the (kinetic energy/potential
energy) of the particles.
ANSWER KEY
Chemistry CPA Final Exam Study Guide 15
For questions 42 – 45, use the following graph:
42. What is the melting point of:
a. substance A? 350 K
b. substance B? 200 K
43. Which substance will melt first? Substance B
44. What is the boiling point of:
a. substance A? 450 K
b. substance B? 250 K
45. Which substance will boil first? Substance B
ANSWER KEY
Chemistry CPA Final Exam Study Guide 16
The Gas Laws
Gas Law Theory
46. Draw and label the graph for each gas law (Boyle’s, Charles’, Gay-
Lussac).
Boyle Charles Gay-Lussac
47. Why is it easier to compress a gas than it is to compress liquids or solids?
Gas particles are very spread out and take up more volume even though their particles are quite small.
48. Why does air escape a tire valve when the cap is removed?
pressure outside the tire is less; systems always move from high to low.
49. Is atmospheric pressure the highest below, at, or very high above sea level?
highest below sea level, lowest very high above sea level
ANSWER KEY
Chemistry CPA Final Exam Study Guide 17
Gas Law Calculations
50. A 500.0 mL sample of gas is collected at 745.0 torr. What will the volume be at 760 torr?
Gas Law: ______Boyle__________
(500)(750)/760 = 493.4 L
51. A 2L sample of gas at 100 K is heated to 150 K. What is the new volume? Gas Law: _______Charles_________
(2)(150)/100 = 3 L
52. If I initially have a gas at a pressure of 12 atm, a volume of 23 liters, and then I raise the pressure to 14 atm, what is the new volume of the gas?
Gas Law: ________Boyle________
(12)(23)/14 = 19.7 L
53. A gas takes up a volume of 17 liters, and a temperature of 299 K. If I raise the temperature to 350 K what is the new volume of the gas?
Gas Law: _______Charles_________
(17)(350)/299 = 19.9 L
ANSWER KEY
Chemistry CPA Final Exam Study Guide 18
54. I have a gas at a volume of 0.5 L and a temperature of 325 K. If I raise the volume to 1.2 L, what will be the new temperature?
Gas Law: _______Charles_________
(325)(1.2)/0.5 = 780 K
55. If I have 21 liters of gas at a temperature of 900 K, what will be the volume of the gas if I decrease the temperature to 750 K?
Gas Law: __________Charles______
(21)(750)/900 = 17.5 L
56. If I have a sample of gas at 300 K and a pressure of 5 atm, what will be the temperature of the gas if I decrease the pressure to 3 atm?
Gas Law: _________Gay-Lussac_______
(300)(3)/5 = 180 K
57. A gas occupies a fixed volume at 285 K at 1 atm. If the pressure increases to 3 atm, what is the new temperature?
Gas Law: _________Gay-Lussac_______
(285)(3)/(1) = 855 K
ANSWER KEY
Chemistry CPA Final Exam Study Guide 19
58. A sample of nitrogen gas (N2) occupies a volume of 0.25 L at a pressure of 2 atm and 22°C. How many moles of N2 gas are there in this sample?
Gas Law:_____________Ideal___ T = 22 + 273 = 295
n = PV/RT (2x0.25)/(0.0821x295)
= 0.021 mol
59. How many grams of N2 gas are there in question 66? (Hint: use moles to grams conversion!)
0.021 mol x 28.02g/1mol = 0.59 g
60. A 4.5 mole sample of gas occupies a volume of 1.3 L at a temperature of 293 K. What is the pressure of the gas?
Gas Law:_______Ideal_________
P = nRT/V
= (4.5)(0.0821)(293)/1.3
= 83.3 atm
ANSWER KEY
Chemistry CPA Final Exam Study Guide 20
Unit 9: Acids & Bases
61. List the properties for acids below.
Sour, pH below 7, caustic, react with metals, produce H+ ions in solution,
electrolyte/conducts electricity, turn litmus paper red
62. List the properties for bases below.
Bitter, pH above 7, caustic, produce OH- ions in solution,
electrolyte/conducts electricity, turn litmus paper blue
63. What happens when an acid is mixed with a base? (Write the general form for the reaction that happens) neutral products are formed:
Acid + base salt + H2O
64. What is the range of the pH scale? 0-14
65. What is the pH range for acids? 0-6.9
66. What is the pH range for bases? 7.1-14
67. What is the pH for a neutral solution? 7
68. pH + pOH = 14
ANSWER KEY
Chemistry CPA Final Exam Study Guide 21
69. Complete the chart
pH pOH Acid , Base,
Neutral
11 3 base
7 7 neutral
12 2 base
2 12 acid
ANSWER KEY
Chemistry CPA Final Exam Study Guide 22
70. Review the sample data table below from a student’s lab and answer the following questions.
Test Property
Test Solutions
A B C
Conductivity Very strong
Very strong none
Litmus Paper Turns Red Turns Blue No change
Phenolphthalein colorless
Pink color change
colorless
pH Test Paper
4.0
10.0
7.0
Universal Indicator
Red
Purple
Green
Reaction with Magnesium
Produces a gas
none
none
ANSWER KEY
Chemistry CPA Final Exam Study Guide 23
Questions to go with the #62 Data Table: A. Is Solution A an acid, base, or neutral? Why? Acid; pH below 7, universal indicator turns red, reacts with magnesium and produces hydrogen gas. B. Is Solution B an acid, base, or neutral? Why? Base; pH above 7, turns ppt pink, turns universal indicator purple, doesn’t react with Mg C. Is Solution C an acid, base, or neutral? Why? Neutral; pH is 7, doesn’t conduct a current, turns universal indicator green, doesn’t react with Mg D. What are the chemical properties that this student tested? Reaction with Mg E. What are the physical properties that this student tested? Conductivity, pH, litmus, phenolphthalein F. What were the qualitative observations this student made? Conductivity, litmus, phenolphthalein, reaction with Mg G. What are the quantitative observations this student made? pH test paper