ANSWER KEY Chemistry CPA Final Exam Study Guide Final Exam ... · PDF fileFinal Exam Date: Wednesday, June 17, 2015 ... 40. When a substance is ... ANSWER KEY Chemistry CPA Final Exam

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


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


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


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


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


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


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


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


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


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


Use this solubility curve to answer the next set of questions (#33- 37) on the following page:

ANSWER KEY


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


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


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


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


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


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


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


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


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


69. Complete the chart

pH pOH Acid , Base,

Neutral

11 3 base

7 7 neutral

12 2 base

2 12 acid

ANSWER KEY


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


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

ANSWER KEY Chemistry CPA Final Exam Study Guide Final Exam ... · PDF fileFinal Exam Date: Wednesday, June 17, 2015 ... 40. When a substance is ... ANSWER KEY Chemistry CPA Final Exam

Documents