ap chemistry midterm review calculators … go on to the next page. ap chemistry midterm review...

1 GO ON TO THE NEXT PAGE.

AP CHEMISTRY Midterm Review

CALCULATORS ARE NOT ALLOWED FOR SECTION I.

*Attempt to complete problems here w/o using calculators.

Note: For all questions, assume that the temperature is 298 K, the pressure is 1.0 atm, and

solutions are aqueous unless otherwise specified.

Directions: Each of the questions or incomplete statements below is followed by four suggested

answers or completions. Select the one that is best in each case and then fill in the corresponding

circle on the answer sheet.

1. When each of the following is

heated to 50℃ and the temperature

is held constant for

5 minutes, which one undergoes

only a physical change?

(A) egg

(B) steak

(C) ice cream

(D) cake batter

Compound Molar Mass

(grams)

Na2O 62.0

MgO 40.3

K2O 94.2

CaO 56.1

2. According to the information in the

table above, a 1.00 g sample of

which of the following contains the

greatest mass of oxygen?

(A) Na2O

(B) MgO

(C) K2O

(D) CaO


3. When 78.0 g of aluminum

hydroxide, Al(OH)3 (molar mass

= 78.0 g/mol), reacts with 49.0 g

sulfuric acid, H2SO4 (molar mass

= 98.1 g/mol), what mass of water

is produced? The equation is

2 Al(OH)3 (s) + 3 H2SO4 (aq)

Al2(SO4)3 (aq) + 6 H2O (l)

(A) 18.0 g

(B) 36.0 g

(C) 54.0 g

(D) 127 g

4. When iron (III) oxide is heated with

carbon, the products are iron metal

and carbon monoxide. Balance the

equation and determine the sum of

the coefficients.

(A) 4

(B) 5

(C) 6

(D) 9

5. Which of the following reaction

mixtures would produce the greatest

amount of product, assuming all

went to completion? Each involves

the reaction symbolized by the

equation.

N2 (g) + 3 H2 (g) 2 NH3 (g)

(A) 2 mol N2 and 4 mol H2

(B) 1 mol N2 and 5 mol H2

(C) 4 mol N2 and 2 mol H2

(D) 5 mol N2 and 1 mol H2

The following information is used for

Questions 6 and 7.

A 20.0-g sample of a hydrated compound is

placed into a crucible and heated. The data

table for this laboratory investigation is

shown below.

Mass of crucible 15.5867 g

Mass of crucible and

hydrated sample

19.7644 g


anhydrous sample after

heating

18.4388 g



second heating

18.0244 g



third heating

18.2422 g

6. Why can we conclude that all of the

water of hydration has been

removed?

(A) The mass of the crucible and

sample increased then

decreased.

(B) The mass of the crucible and

sample decreased after each

heating.

(C) The mass of the crucible and

sample decreased due to the

water of hydration being

removed.

(D) The mass of the crucible and

sample remained constant after

the second heating.

7. What is the mass of the water of

hydration in the hydrate?

(A) 0.4146 g

(B) 1.7402 g

(C) 2.4325 g

(D) 4.1777 g


8. A compound contains 1.10 mol of K,

0.55 mol of Te, and 1.65 mol of O.

What is the empirical formula of this

compound?

(A) KTeO

(B) K2TeO3

(C) K2TeO6

(D) K4TeO6

9. Propane gas burns in excess oxygen

gas. When the equation for this

reaction is correctly balanced and all

coefficients are reduced to their

lowest whole-number terms, the

coefficient for O2 is

(A) 4

(B) 5

(C) 7

(D) 10

10. When 8.0 g of N2H4 (32 g/mol) and

92 g of N2O4 (92 g/mol) are mixed

together and react according to the

equation above, what is the

maximum mass of H2O that can be

produced?

2 N2H4(g) + N2O4(g)

--> 3 N2(g) + 4 H2O(g)

(A) 9.0 g

(B) 18 g

(C) 36 g

(D) 72 g

11. What is the correct name for Fe2S3?

(A) diiron trisulfide

(B) iron sulfide

(C) iron (II) sulfide

(D) iron (III) sulfide


12. A 10.00-g piece of metal is

submerged in a graduated cylinder

initially containing 20.00 mL of

water. With the metal in the

cylinder, the level of the water is

recorded as 21.40 mL. Determine

the identity of the metal.

(A) aluminum (density = 2.70 g/mL)

(B) zinc (density = 7.13 g/mL)

(C) silver (density = 10.49 g/mL)

(D) gold (density = 19.32 g/mL)

13. Atoms of Mg combine with atoms

of F to form a compound. Atoms of

which of the following elements

combine with atoms of F in the

same ratio?

(A) Li

(B) Ba

(C) Al

(D) Cl

14. Which of the following is NOT an

accepted name for the formula

given?

(A) CH3OH ... methanol

(B) CuO ... copper (I) oxide

(C) FeCl3 ... iron (III) chloride

(D) H2SO4 ... sulfuric acid

15. When a 3.22 g sample of an

unknown hydrate of sodium sulfate,

Na2SO4 · x H2O (s), is heated, H2O

(molar mass 18 g) is driven off. The

mass of the anhydrous Na2SO4(s)

(molar mass 142 g) that remains is

1.42 g. The value of x in the hydrate

is

(A) 1.8

(B) 6.0

(C) 10.

(D) 20.

16. A 6.0 mol sample of C3H8 (g) and a

20. mol sample of Cl2 (g) are placed

in a previously evacuated vessel,

where they react according to the

equation below. After one of the

reactants has been totally consumed,

how many moles of HCl (g) have

been produced?

C3H8 (g) + 4 Cl2 (g)

C3H4Cl4 (g) + 4 HCl (g)

(A) 4.0 mol

(B) 8.0 mol

(C) 20. mol

(D) 24 mol


17. What is the name of an aqueous

solution that contains HNO2?

(A) Nitric acid

(B) Nitrous acid

(C) Hydrogen nitrite

(D) Hydrogen nitrogen dioxide

18. The empirical formula for a

compound made from element X

(molar mass = 79.0 g/mol) that is

21.0% nitrogen by mass is

(A) XN

(B) XN2

(C) X2N3

(D) X3N2

19. Which of the following compounds

contains the greatest percent by

mass of nitrogen?

(A) NH3

(B) HCN

(C) N2O

(D) NI3

20. In a Bunsen burner, methane reacts

with oxygen to produce carbon

dioxide and water. What mass of

water can be produced from 16

grams of methane and excess

oxygen?

(A) 8.0 g

(B) 16 g

(C) 18 g

(D) 36 g

21. When the equation below is balanced

and all coefficients reduced to lowest

whole-number terms, the coefficient

for OH–(aq) is

... Li3N(s) + ... H2O(l)

... Li+(aq) + ... OH–

(aq) + …NH3(g)

(A) 1

(B) 2

(C) 3

(D) 6


22. Which of the following techniques is

most appropriate for the recovery of

solid CaCO3 from an aqueous

solution of KNO3?

(A) Paper chromatography

(B) Filtration

(C) Distillation

(D) Evaporation to dryness

The following information is used for

Question 23.

Mass of an empty container 3.0 grams

Mass of the container plus the

solid sample

25.0 grams

Volume of the solid sample 11.0 cm3

23. The data above were gathered in

order to determine the density of an

unknown solid. The density of the

sample should be reported as

(A) 0.5 g/cm3

(B) 0.50 g/cm3

(C) 2.0 g/cm3

(D) 2.00 g/cm3

24. Substances X and Y that were in a

heterogeneous mixture were

separated in the laboratory using the

technique of fractional distillation.

This fractional distillation is

possible because substances X and

Y have different

(A) boiling points

(B) melting points

(C) densities

(D) solubilities

25. How many grams of calcium nitrate,

Ca(NO3)2, contains 24 g of oxygen

atoms?

(A) 164 g

(B) 96 g

(C) 62 g

(D) 41 g


26. The mass of element Q found in 1.00

mole of each of four different

compounds is 38.0 g, 57.0 g, 76.0 g, and

114 g, respectively. A possible atomic

mass of Q is

(A) 12.7

(B) 19.0

(C) 27.5

(D) 38.0

27. The mineral magnesite contains

magnesium carbonate, MgCO3 (molar

mass = 84 g/mol) and other impurities.

When a 1.26-g sample of magnesite

was dissolved in hydrochloric acid, 0.22

g of CO2 was generated. If the

magnesite contained no carbonate other

than MgCO3, what was the percent

MgCO3 by mass in the magnesite? The

equation is

MgCO3 (s) + 2 HCl (aq)

MgCl2 (aq) + H2O (l) + CO2 (g)

(A) 25 %

(B) 33 %

(C) 50.%

(D) 67%

28. Which of the following would produce

the least mass of CO2 if burned

completely in oxygen gas?

(A) 10.0 g CH3OH

(B) 10.0 g C2H4

(C) 10.0 g C2H6

(D) 10.0 g C4H5OH

29. If a metal X forms an ionic chloride

with the formula XCl2, then which of

the following formulas is most likely to

be that of a stable sulfide of X?

(A) XS

(B) XS2

(C) X2S

(D) X2S2

30. What is the empirical formula of a

hydrocarbon that is 10.0 percent

hydrogen by mass?

(A) C2H3

(B) C3H5

(C) C3H2

(D) CH4

31. The safest and most effective emergency procedure to treat an acid splash on skin is to

do which of the following immediately?

(A) Dry the affected area with paper towels

(B) Sprinkle the affected area with powdered Na2SO4(s)

(C) Flush the affected area with water and then with a dilute NaOH solution

(D) Flush the affected area with water and then with a dilute NaHCO3 solution


32. A rigid metal tank contains oxygen gas. Which of the following applies to the gas in the

tank when additional oxygen is added at constant temperature?

(A) The volume of the gas increases.

(B) The pressure of the gas decreases.

(C) The average speed of the gas molecules remains the same.

(D) The average distance between the gas molecules increases.

33. A 40.0 mL sample of 0.25 M KOH is added to 60.0 mL of 0.15 M Ba(OH)2. What is the

molar concentration of OH–(aq) in the resulting solution? (Assume that the volumes are additive.)

(A) 0.10 M

(B) 0.19 M

(C) 0.28 M

(D) 0.40 M

34. In which of the following species does sulfur have the same oxidation number as it does in

H2SO4?

(A) SO2Cl2

(B) S2O32-

(C) S2-

(D) H2SO3

35. A 0.03 mol sample of NH4NO3(s) is placed in a 1 L evacuated flask, which is then sealed

and heated. The NH4NO3(s) decomposes completely according to the balanced equation above.

The total pressure in the flask measured at 400 K is closest to each of the following?

(A) 3 atm

(B) 1 atm

(C) 0.5 atm

(D) 0.1 atm

(E)

36. A 0.20 mol sample of MgCl2(s) and a 0.10 mol sample of KCl(s) are dissolved in water and

diluted to 500 mL. What is the concentration of Cl- in the solution?

(A) 0.15 M

(B) 0.30 M

(C) 0.50 M

(D) 1.0 M


37. What volume of O2(g) is required to react with excess CS2(l) to produce 4.0 L of CO2(g)?

(Assume all gases are measured at 0˚C and 1 atm.) The balanced equation is

CS2 (l) + 3 O2 (g) CO2 (g) + 2 SO2 (g)

(A) 12 L

(B) 22.4 L

(C) 1/3 22.4 L

(D) 3 22.4 L

38. A 1.0 L sample of an aqueous solution contains 0.10 mol of NaCl and 0.10 mol of CaCl2.

What is the minimum number of moles of AgNO3 that must be added to the solution in order

to precipitate all of the Cl- as AgCl(s) ?

(A) 0.10 mol

(B) 0.20 mol

(C) 0.30 mol

(D) 0.40 mol

39. Approximately what mass of CuSO4•5H2O (250 g mol-1) is required to prepare 250 mL of

0.10 M copper(II) sulfate solution?

(A) 4.0 g

(B) 6.3 g

(C) 34 g

(D) 85 g

40. C3H8 (g) + 5 O2 (g) 3 CO2 (g) + 4 H2O (l)

In the reaction represented above, what is the total number of moles of reactants consumed

when 1.00 mole of CO2 (g) is produced?

(A) 0.33 mol

(B) 1.33 mol

(C) 1.50 mol

(D) 2.00 mol


Questions 41-42 refer to the figures below. The figures show portions of a buret used in a

titration of an acid solution of known concentration with a saturated solution of Ba(OH)2. The

acid contains one acidic hydrogen. Figures 1 and 2 show the level of the Ba(OH)2 solution at the

start and at the endpoint of the titration, respectively. Phenolphthalein was used as the indicator

for the titration.

41. Which is a mathematical expression for calculating the number of moles of acid in the flask?

(A) (Volume of Ba(OH)2 in L × molarity of Ba(OH)2) / 2

(B) Volume of Ba(OH)2 in L × molarity of Ba(OH)2

(C) (Volume of Ba(OH)2 in L × molarity of Ba(OH)2) × 2

(D) Volume of Ba(OH)2 in L × molarity of Ba(OH)2 / 4

42. The volume of saturated Ba(OH)2 used to neutralize the acid was closest to

(A) 6.60 mL

(B) 22.80 mL

(C) 23.02 mL

(D) 23.20 mL

43. What mass of KBr (molar mass 119 g mol-1) is required to make 250. mL of a 0.400 M KBr

solution?

(A) 1.19 g

(B) 2.50 g

(C) 11.9 g

(D) 47.6 g


Gas Amount

Ar 0.35 mol

CH4 0.90 mol

N2 0.25 mol

44. Three gases in the amounts shown in the table above are added to a previously evacuated

rigid tank. If the total pressure in the tank is 3.0 atm at 25℃, the partial pressure of N2 (g) in

the tank is closest to

(A) 0.50 atm

(B) 0.33 atm

(C) 0.25 atm

(D) 0.17 atm

45. At which of the following temperatures and pressures would a real gas be most likely to

deviate from ideal behavior?

Temperature (K) Pressure (atm)

(A) 500 0.01

(B) 300 0.01

(C) 200 5

(D) 100 50

46. The frequency of a photon that has an energy of 3.7 x 10-18 J is __________ Hz.

A) 5.4 x 10-8 B) 5.6 x 1015 C) 1.8 x 10-16 D) 2.5 x 10-15 E) 2.5 x 1015

47. Ham radio operators often broadcast on the 6-meter band. The frequency of this

electromagnetic radiation is __________ Hz.

A) 5.0 x 107 B) 2.0 x 107 C) 2.0 x 106 D) 2.0 x 108 E) 5.0 x 108

48. The lines in the emission spectrum of hydrogen result from __________.

A) electrons given off by hydrogen as it cools

B) decomposing hydrogen atoms

C) electrons given off by hydrogen when it burns

D) energy given off in the form of visible light when an electron moves from a higher energy

state to a lower energy state

E) protons given off when hydrogen burns

49. The electron configuration of a ground-state Ag atom is __________.

A) [Kr]5s14d10 B) [Kr]5s24d10 C) [Ar]4s24d9 D) [Kr]5s23d9 E) [Ar]4s14d10


50. Which orbital diagram denotes an atom in its ground state?

A)

B)

C)

D)

E)

Consider the following electron configurations to answer questions 51 – 53:

(i) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1

(ii) 1s2 2s2 2p6 3s2 3p5

(iii) 1s2 2s2 2p6 3s2 3p6 4s2 3d8

(iv) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6

(v) 1s2 2s2 2p4 3s1

51. An example of an electron configuration of a transition metal is __________.

A) (i) B) (ii) C) (iii) D) (iv) E) (v)

52. An example of an excited state electron configuration for fluorine is __________.

A) (i) B) (ii) C) (iii) D) (iv) E) (v)

53. Which of the electron configurations represents the configuration for chlorine?

A) (i) B) (ii) C) (iii) D) (iv) E) (v)

54. Atomic radius generally increases as we move __________.

A) up a group and from right to left across a period

B) down a group; the period position has no effect

C) up a group and from left to right across a period

D) down a group and from right to left across a period

E) down a group and from left to right across a period

55. Which one of the following has the smallest radius?

A) P B) Na C) Br D) Cl E) Fe

56. Which one of the following atoms has the largest radius?

A) Co B) Sr C) I D) Ca E) Ba


Consider the following electron configurations to answer the questions that follow:

(i) [Kr] 5s1

(ii) [Ne] 3s2 3p5

(iii) [Ar] 4s2 3d10 4p4

(iv) [Ne] 3s2 3p6

(v) [Ar] 4s1

57. The electron configuration of the atom that is expected to have the lowest first ionization

energy is __________.

A) (i) B) (ii) C) (iii) D) (iv) E) (v)

58. The electron configuration of the atom that is expected to have the highest first ionization

energy is __________.

A) (i) B) (ii) C) (iii) D) (iv) E) (v)

59. The first ionization energies of the elements __________ as you go from left to right across a

period of the periodic table, and __________ as you go from the bottom to the top of a group

in the table.

A) increase, increase

B) increase, decrease

C) decrease, increase

D) decrease, decrease

E) are completely unpredictable

60. Of the choices below, which gives the order for first ionization energies?

A) Cl > S > Al > Ar > Si

B) S > Si > Cl > Al > Ar

C) Al > Si > S > Cl > Ar

D) Ar > Cl > S > Si > Al


AP CHEMISTRY – Free Response Question Midterm Review

Section II

YOU MAY USE YOUR CALCULATOR FOR THIS SECTION.

Write your response in the space provided following each question. Examples and equations may

be included in your responses where appropriate. For calculations, clearly show the method used

and the steps involved in arriving at your answers. You must show your work to receive credit

for your answer. Pay attention to significant figures.

1.

2 H2O2(aq) → 2 H2O(l) + O2(g)

The mass of an aqueous solution of H2O2 is 6.951 g. The H2O2 in the solution decomposes

completely according to the reaction represented above. The O2(g) produced is collected in an

inverted graduated tube over water at 23.4°C and has a volume of 182.4 mL when the water levels

inside and outside of the tube are the same. The atmospheric pressure in the lab is 762.6 torr, and

the equilibrium vapor pressure of water at 23.4°C is 21.6 torr.

(a) Calculate the partial pressure, in torr, of O2(g) in the gas-collection tube.

(b) Calculate the number of moles of O2(g) produced in the reaction.

(c) Calculate the mass, in grams, of H2O2 that decomposed.

(d) Calculate the percent of H2O2 , by mass, in the original 6.951 g aqueous sample.


(e) Write the oxidation number of the oxygen atoms in H2O2 and the oxidation number of the

oxygen atoms in O2 in the appropriate cells in the table below.

Substance Oxidation Number

of Oxygen Atoms

H2O2

O2

2. An experiment is to be performed to determine the standard molar enthalpy of neutralization

of a strong acid by a strong base. Standard school laboratory equipment and a supply of

standardized 1.00-molar HCl and standardized 1.00-molar NaOH are available.

(a) What equipment would be needed?

(b) What measurements should be taken?

(c) Without performing calculations, describe how the resulting data should be used to obtain the

standard molar enthalpy of neutralization, using the equation q = mCΔT.

(d) When a class of students performed this experiment, the average of the results was -55.0

kilojoules per mole. The accepted value for the standard molar enthalpy of neutralization of a

strong acid by a strong base is -57.7 kilojoules per mole. Propose two likely sources of

experimental error that could account for the result obtained by the class.

(e) If 0.50 M hydrochloric acid and 0.50 M sodium hydroxide were used, would the calculated

value of q increase, decrease, or stay the same when compared to the first experiment? What

about the molar enthalpy of neutralization?


3. Answer the following questions that relate to the analysis of chemical compounds.

(a) A compound containing the elements C, H, N, and O is analyzed. When a 1.2359 g sample

is burned in excess oxygen, 2.241 g of CO2(g) is formed. The combustion analysis also

showed that the sample contained 0.0648 g of H.

(i) Determine the mass, in grams, of C in the 1.2359 g sample of the compound.

(ii)When the compound is analyzed for N content only, the mass percent of N is found to be

28.84 percent. Determine the mass, in grams, of N in the original 1.2359 g sample of the

compound.

(iii) Determine the mass, in grams, of O in the original 1.2359 g sample of the compound.

(iv) Determine the empirical formula of the compound.

(v) The molar mass of the compound is 188 g mol-1. Calculate the molecular formula of

the compound.


4. Suppose that a stable element with atomic number 119, symbol Q, has been discovered.

(a) Write the ground-state electron configuration for Q, showing only the valence-shell electrons.

(b) Would Q be a metal or a nonmetal? Explain in terms of electron configuration.

(c) On the basis of periodic trends, would Q have the largest atomic radius in its group or would

it have the smallest? Explain in terms of electronic structure.

(d) On the basis of periodic trends, would Q have the largest ionization energy in its group or

would it have the smallest? Explain in terms of electronic structure.

(e) What would be the most likely charge of the Q ion in stable ionic compounds?

(f) Write a balanced equation that would represent the reaction of Q with water.

(g) Assume that Q reacts to form an oxide compound.

(i) Write the ionization equation for atomic oxygen that requires 13.6 eV of energy.

(ii) Write the formula for the compound formed between Q and the oxide ion, O2–.

(ii) Predict whether or not the compound would be soluble in water. Explain your reasoning.

ap chemistry midterm review calculators … go on to the next page. ap chemistry midterm review...

Documents