Chemistry 2202 UNIT 1 Year End Review June 2011

Part 1

Mass and Moles

2008

1. How many neutrons are in phosphorus-32?

(A) 15

(B) 17

(C) 31

(D) 32

2. How many molecules are in 1.75 mol of OF2?

(A) 3.44 x 1023

(B) 6.88 x 1023

(C) 1.05 x 1024

(D) 2.11 x 1024

3. What is a mole?

(A) 12 g of carbon-12

(B) 19 g of fluorine-19

(C) 22.4 L of O2(g) at 1000C

(D) 6.02 x 1023 atoms of H in H2O

4. What is the molar mass of MgCO3 ☻ 5H2O?

(A) 102.34 g/mol

(B) 110.42 g/mol

(C) 174.42 g/mol

(D) 205.05 g/mol

5. Which has the greatest volume?

(A) 0.50 mol of helium gas at S.T.P.

(B) 2.0 L of ice at 00C

(C) 6.0 L of oxygen at 250C and atmospheric pressure

(D) 150 mL of water at room temperature

6. Which gas would have a mass of 2.500 g and a volume of 2.775 L at S.T.P.?

(A) Ar(g)

(B) He(g)

(C) Kr(g)

(D) Ne(g)

2009 Sample

(A) 93.72 amu

(B) 280.78 amu

(C) 280.85 amu

(D) 281.16 amu

1. How many neutrons are in an atom of magnesium-25?

(A) 12

(B) 13

(C) 25

(D) 37

2. How many moles are in a sample that contains 2.71 x 1024 atoms of aluminum?

(A) 0.222 mol

(B) 4.50 mol

(C) 6.02 x 1023 mol

(D) 6.13 x 1048

3. What is the molar mass of lead (II) sulfate, PbSO4

(A162.00 g/mol

(B) 255.26 g/mol

(C) 303.26 g/mol

(D) 1021.04 g/mol

4. How many moles are in 7.500 g of NH4Br (Molar mass = 97.95 g/mol)?

(A) 0.07657 mol

(B) 13.06 mol

(C) 97.95 mol

(D) 734.6 mol

14. What is the average atomic mass of the newly found element Nonamium (No) given

the following percent abundances:

2009

1. What is the isotope name of ?

(A)copper-29

(B)copper-39

(C)copper-68

(D)copper-97

2. Buckminsterfullerines are large molecules that resemble a see-through soccer ball. These molecules are composed entirely of carbon atoms. What is the chemical formula for a buckminsterfullerene that has a molar mass of 841 g/mol?

(A)C60

(B)C70

(C)C829

(D)C853

3.What is the molar mass of calcium hydroxide, ?

(A)38.00 g/mol

(B)58.10 g/mol

(C)74.10 g/mol

(D)116.20 g/mol

4.How many calcium atoms are there in a 3.00 mol sample?

(A)

(B)

(C)

(D)

5. What is the mass of 0.300 mol of (molar mass = 136.15 g/mol)?

(A) g

(B)40.8 g

(C)48.9 g

(D) g

6. How many molecules of (molar mass = 180.18 g/mol) are present in a 5.50 g sample?

(A)

(B)

(C)

(D)

12.Large deposits of gypsum, an ionic hydrate, are located in western Newfoundland. By mass, what percentage of gypsum, , is water?

(A)6.210%

(B)20.93%

(C)66.67%

(D)79.07%

14.At and 100.0 kPa, the molar volume of a gas is 24.8 L/mol. What volume would molecules of helium occupy under these conditions?

(A)0.0325 L

(B)0.805 L

(C)18.0 L

(D)20.0 L

2010

1.Carbon-12 and carbon-14 are isotopes of carbon. How are these isotopes different?

(A)number of electrons

(B)number of neutrons

(C)number of photons

(D)number of protons

2.How many atoms are in 1.00 mol of beryllium?

(A)9.01

(B)22.4

(C)6.02 x 1023

(D)1.20 x 1047

3.Which isotope has 52 protons and 75 neutrons?

(A)Rhenium - 75

(B)Rhenium - 127

(C)Tellurium - 52

(D)Tellurium - 127

4.What is the molar mass of Al2(SO4)3?

(A)214.17 g/mol

(B)278.03 g/mol

(C)342.17 g/mol

(D)450.09 g/mol

15.What volume does 22.2 g of chlorine gas, Cl2 (g), occupy at STP?

(A)7.01 L

(B)14.0 L

(C)35.8 L

(D)71.8 L

2011

1. What is the number of neutrons in

(A)12

(B) 14

(C) 26

(D) 38

2.Which quantity represents a mole?

(A) 1 g of hydrogen-1

(B) 2.24 mL of hydrogen-1

(C) 6.02 atoms of carbon-12

(D) 12 g of carbon-12

3.What is the number of moles in 3.5 x 1023 molecules of CH4 ?

(A) 4.7 x 10-48 mol

(B) 0.58 mol

(C) 1.7 mol

(D) 2.1 x 1047 mol

4.An element has two naturally occurring isotopes. One isotope has a natural abundance of 60.11% and a mass of 68.93 amu. The second isotope has a natural abundance of 39.89% and a mass of 70.96 amu. What is the average atomic mass of the element?

(A) 58.71 amu

(B) 65.38 amu

(C) 69.74 amu

(D) 70.59 amu

5.What is the molar mass of Ba(NO3)2?

(A) 213.35 g/mol

(B) 247.34 g/mol

(C) 261.35 g/mol

(D) 384.67 g/mol

6.What is the number of moles in 5.00 g of He(g)?

(A) 0.0500 mol

(B) 0.800 mol

(C) 1.25 mol

(D) 20.0 mol

7.What is the volume of 2.45 mol of Ar(g) at STP?

(A) 0.109 L

(B) 0.914 L

(C) 54.9 L

(D) 97.9 L

Mass and Moles Part 11 Question

2008

41. (d) Calculate the volume of chlorine which contains 1.20 x 1024 molecules of Cl2(g) at S.T.P.

41. (e) A 3.34 g sample of a hydrated compound, SrS2O3 xH2O contains 2.30 g of SrS2O3.

How many water molecules, x, are hydrated for each strontium ion?

2009 Sample

41. c. What is the mass of 4.00 L of ammonia gas (NH3 (g)) at STP?

2009

41. c. Calculate the volume of 10.0 g of nitrogen dioxide, at STP.

41. g. Naturally occurring magnesium exists as a mixture of three isotopes. Mg-24 has an atomic mass of 23.985 amu and a relative abundance of 78.70 %. Mg-25 has an atomic mass of 24.985 amu and a relative abundance of 10.13%. The average atomic mass of magnesium is 24.31 amu. Calculate the atomic mass of the remaining isotope.

2010

41.(a)Data was collected on three isotopes of a newly discovered element, Novium. Calculate the average atomic mass.

Isotope Name

Percent Abundance (%)

Atomic Mass (amu)

Novium-272

70.69

271.853

Novium -276

17.71

275.985

Novium -280

11.60

279.859

41. (b) Calculate the number of molecules of propanoic acid (C2H5COOH) in a 3.45 g sample.

41. g. Copper exists as two naturally occurring isotopes. One isotope has an atomic

mass of 62.93 amu and a relative abundance of 69.1%. The percent

abundance of the other isotope is 30.9%. If the average atomic mass of

copper is 63.55 amu, calculate the atomic mass of the other isotope.

2011

41(b)Which element would have 5.200 x 1022 atoms with a mass of 5.489 g?

41.(c)Given the reaction:

4 Al(s) + 3 O2(g) → 2 Al2O3(s)

Calculate the mass of aluminum needed to react completely with 325 mL of oxygen gas at STP.

% Compostion, Empirical Formula, Molecular Formula Part 1 Questions

2008

7. What is the percent composition of H in an organic compound containing only C, H and O if

the percent composition of C and O are 37.47 % and 49.92 %, respectively?

(A) 9.454 %

(B) 12.61 %

(C) 87.39 %

(D) 90.55 %

8. What is the percent composition of hydrogen in ammonium chloride, NH4Cl?

(A) 1.89 %

(B) 2.00 %

(C) 7.55 %

(D) 8.00 %

9. What is the identity of "X" in the compound Na2X, given that the percent composition of

sodium in the compound is 58.91% ?

(A) Cl

(B) F

(C) O

(D) S

Sample 2009

5. The molar mass of a compound with the empirical formula of CH2O is 180.16 g/mol.

What is the molecular formula of the compound?

(A) CH2O

(B) C4H4O8

(C) C4H8O4

(D) C6H12O6

6. Which unit expresses molar concentration?

(A) g/mol

(B) L/mol

(C) mol/g

(D) mol/L

2010

5. What is the percent composition of water in Plaster of Paris, (CaSO4)2 • H2O?

(A)6.207%

(B)13.81%

(C)33.09%

(D)93.79%

2011

8.A compound contains 3.38 g of P and 11.62 g of Cl. What is the percent composition of P?

(A) 22.5 %

(B) 45.1 %

(C) 54.9 %

(D) 77.5 %

9.What is the percent composition of water in gypsum, CaSO4.2H2O(s)?

(A) 2.346 %

(B) 10.47 %

(C) 20.93 %

(D) 79.07 %

10.What is the empirical formula of a compound which has the molecular formula of C9H12O3?

(A) C2.25H3O

(B) C3H4O1.33

(C) C3H4O

(D) C9H12O3

% Compostion, Empirical Formula, Molecular Formula Part 11 Questions

2008

41. (a) A compound contains 82.63% carbon and 17.37% hydrogen by mass.

(i) Find the empirical formula of the compound.

(ii) Find the molecular formula of the compound if its molar mass is 58.14 g/mol.

Sample 2009

41. a. A compound is found to have a % composition of 72.71% oxygen and 27.29% carbon. Determine the empirical formula of the compound.

2009

41. a. Percent composition analysis reveals that a compound is 71.06% cobalt and 28.94% oxygen. Determine the empirical formula.

b. A compound has a molar mass of 84.18 g/mol. Percent composition analysis revealed that the compound has an empirical formula of . Determine the molecular formula of the compound.

2010

41.(c)A compound’s molar mass is 283.88 g/mol. Its percentage composition is 43.64% P and 56.36% O. Determine the molecular formula for this compound.

2011

41.(a)A compound contains 47.98 % C, 9.414 % H and 42.61 % O. What is the

empirical formula of the compound?

Stoichiometry Part 1 Questions

2008

16. According to the equation below, how many moles of oxygen will combine with 2.00 mol of

phosphorus?

P4(g) + 5 O2 (g) → 2 P2O5(s)

(A) 2.00 mol

(B) 2.50 mol

(C) 7.00 mol

(D) 10.0 mol

17. For the reaction below, how much A is required to form 5.00 g of B and 3.00 g of C?

2 A → B + C

(A) 2.00 g

(B) 8.00 g

(C) 15.0 g

(D) 16.0 g

18. How is Plaster of Paris related to gypsum?

(A) Plaster of Paris can be made by dehydrating gypsum.

(B) Plaster of Paris decomposes over time into gypsum.

(C) Plaster of Paris forms when water is added to gypsum

(D) Plaster of Paris undergoes combustion to produce gypsum.

Sample 2009

10. Given the balanced equation

12. Sulfur dioxide, SO2, which is produced as a result of burning fuel, is a compound that causes acid rain. It can be removed from smokestacks by reacting it with calcium

carbonate, CaCO3

How many moles of water are needed to react with 50 moles of SO2 ?

(A) 2 mol

(B) 50 mol

(C) 52 mol

(D) 100 mol

2009

7. Given the balanced chemical equation,

what volume of should be produced at STP by the reaction of 0.208 mol of with sufficient quantities of and ?

(A)0.104 L

(B)2.33 L

(C)4.66 L

(D)9.30 L

8. In a lab activity, students react solid copper in a silver nitrate solution:

If 5 mol of is mixed with 3 mol of , which is the limiting reagent?

(A)

(B)

(C)

(D)

9.How many moles of are produced by the complete combustion of 3.5 mol of ?

(A)3.5 mol

(B)12 mol

(C)21 mol

(D)42 mol

2010

14.If 6.76 mol of Fe(s) reacts with excess O2(g), how many moles of solid product should be formed?

4 Fe (s) + 3 O2 (g) 2 Fe2O3 (s)

(A)3.38 mol

(B)5.07 mol

(C)9.01 mol

(D)13.5 mol

16.A chemist completes a chemical reaction in the laboratory; 2.34 g of product are recovered. What does this mass represent?

(A)actual yield

(B)percent difference

(C)percent yield

(D)theoretical yield

17.A candle completely burns in air until there is no wax left. Which term best describes the wax?

(A)actual yield

(B)excess reagent

(C)limiting reagent

(D)theoretical yield

18.If 0.269 mol of nickel are recovered in an experiment and the theoretical yield is 0.556 mol, what is the percent yield?

(A)48.4%

(B)51.6%

(C)55.6%

(D)207%

2011

17.For the reaction below, 2.50 mol of P4(s) reacts with excess O2(g). How many moles of P2O5(s) will form?

P4(s) + 5 O2(g) → 2 P2O5(s)

(A) 1.25 mol

(B) 2.50 mol

(C) 5.00 mol

(D) 10.0 mol

18.A student measured out 1.57 g of product in a chemical reaction in which she expected to produce 2.04 g of product. What was the percent yield of the experiment?

(A) 23.1 %

(B) 43.4 %

(C) 56.5 %

(D) 77.0 %

Which will conduct electricity in the solid state?

(A) CuZn

(B) NiNO3

(C) SiO2

(D) SO2

How many valence electrons does phosphorus have?

(E) 1

(F) 3

(G) 5

(H) 15

Which is the correct formula for a compound containing phosphorus and hydrogen atoms?

(I) PH

(J) PH4

(K) P2H4

(L) P2H6

Stoichiometry Part 11 Questions

2008

41. (c) Zinc metal reacts with aluminum chloride to precipitate aluminum metal.

2 AlCl3(aq) + 3 Zn(s) ! 3 ZnCl2(aq) + 2 Al(s)

(i) If excess AlCl3(aq) reacts with 2.35g of Zn(s), calculate the theoretical yield of

Al(s) expected, in grams.

(ii) If the experiment produced 0.515 g of Al(s), calculate the percent yield for the

reaction.

41. (f) An unknown alkaline earth metal (Group IIA) "M" reacts with a solution of sodium

fluoride, NaF(aq), in a single replacement reaction:

M(s) + 2 NaF (aq) ! 2 Na(s) + MF2(aq)

When 5.000 g of the metal "M" reacts, 5.736 g of Na(s) precipitates. What is the

identity of the metal "M"? Show all workings.

Sample 2009

41.

41. e

2009

41. e.(i)A student reacts 50.0 g of with excess . Calculate the theoretical yield of in grams.

(ii)If the actual yield of produced in part (i) was 24.6 g, determine the percent yield.

2010

3 41.(f)Calculate the volume of hydrogen gas, H2, required to produce 154 g of ammonia, NH3, at STP. (Molar mass of NH3 = 17.04 g/mol)

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

SOLUTIONS/DILUTIONS

Part 1 Questions

2008

10. What is meant by the term ‘aqueous’ when referring to a chemical substance?

(A) It is dissolved in water

(B) It is highly acidic

(C) It is in the liquid phase

(D) It is not very soluble in water

11. Which term has the same meaning as the chemistry term ‘solution’?

(A) heterogenous mixture

(B) homogeneous mixture

(C) immiscible mixture

(D) irreversible mixture

12. The solubility of KNO3 at 25oC is 38g/100mL in H2O. A beaker contains 76g of KNO3

dissolved completely in 200mL of water at 25oC. Which term describes the solution?

(A) dilute

(B) saturated

(C) supersaturated

(D) unsaturated

13. Which substance is considered to be an electrolyte?

(A) C6H6

(B) CH3OH

(C) H2O

(D) KBr

14. What volume of 3.00 mol/L HCl(aq) would contain 0.500 mol of hydrochloric acid?

(A) 0.167L

(B) 0.667L

(C) 1.50L

(D) 6.00L

Sample 2009

2009

10.Which term best describes a solution that cannot dissolve any more solute at a constant temperature?

(A)dilute

(B)polyunsaturated

(C)saturated

(D)unsaturated

11. What is the concentration of 0.250L solution that contains 2.50 g of (molar mass = 310.18 g/mol)?

(A)mol/L

(B)mol/L

(C) mol/L

(D)194 mol/L

13. What mass of NaOH (molar mass = 40.00 g/mol) is present in 0.250 L of a 0.100 mol/L solution?

(A) g

(B)1.00 g

(C)16.0 g

(D) g

14.At and 100.0 kPa, the molar volume of a gas is 24.8 L/mol. What volume would molecules of helium occupy under these conditions?

(A)0.0325 L

(B)0.805 L

(C)18.0 L

(D)20.0 L

15.Which is the correct equation for the dissociation of potassium phosphate, ?

(A)

(B)

(C)

(D)

16. Which has low solubility in water?

(A)

(B)

(C)

(D)Mg

17. What is the concentration of nitrate ions in a 0.60 mol/L solution of lead(IV) nitrate, ?

(A)0.15 mol/L

(B)0.60 mol/L

(C)1.8 mol/L

(D)2.4 mol/L

18. After combining solutions of sodium carbonate and calcium nitrate, a student filtered the reaction mixture to collect a precipitate of calcium carbonate. Which occurs if the precipitate is weighed before it is completely dry?

(A)% yield is higher than it should be

(B)% yield is lower than it should be

(C)theoretical yield is higher than it should be

(D)theoretical yield is lower than it should be

2010

7.Which is the most concentrated solution?

(A)1.23 mol/L

(B)5.83 mol/L

(C)7.60 mol/L

(D)8.00 mol/L

8.Which has high solubility in water?

(A)AgBr

(B)AgNO3

(C)Ag2S

(D)Ag2SO4

9.Which defines an electrolytic solution?

(A)bright colored

(B)conducts electricity

(C)conducts heat

(D)contains excess solute

11.Sodium chloride, NaCl(s), crystals are added to an existing sodium chloride solution. The crystals settle at the bottom of the container without undergoing a change in mass. Which describes the original solution?

(A)monounsaturated

(B)saturated

(C)supersaturated

(D)unsaturated

12.A lab technician prepares a dilute solution of hydrochloric acid. If 50.0 mL of 2.50 mol/L hydrochloric acid is added to 450.0 mL of water, what is the new concentration?

(A)0.250 mol/L

(B)0.278 mol/L

(C)3.60 mol/L

(D)4.00 mol/L

13.What is the correct dissociation equation for iron (III) sulfate?

(A)Fe2(SO4)3 (s) Fe3+ (aq) + SO42- (aq)

(B)Fe2(SO4)3 (s) Fe3+ (aq) + SO42- (aq)

(C)Fe2(SO4)3 (s) 2 Fe3+ (aq) + 3 SO42- (aq)

(D)Fe2(SO4)3 (s) 3 Fe2+ (aq) + 3 SO42- (aq)

2011

11.What is the percent by volume of an ethanol disinfectant solution if 50.0 mL of ethanol is dissolved in water to make 3.00 L of solution?

(A) 1.67%

(B) 6.00%

(C) 94.0%

(D) 98.3%

12.The solubility of MgCl2 is 25 g/100 mL of water. Which describes a saturated solution of magnesium chloride?

(A) 5.0 g of MgCl2 in 100 mL water

(B) 15 g of MgCl2 in 100 mL water

(C) 25 g of MgCl2 in 100 mL water

(D) 45 g of MgCl2 in 100 mL water

13.What is the final concentration of a solution which is prepared by diluting 375 mL of a 0.420 mol/L solution in a volumetric flask to a final volume of 0.500 L?

(A) 0.315 mol/L

(B) 0.446 mol/L

(C) 315 mol/L

(D) 446 mol/L

14.The cross-section sketch of the neck of a volumetric flask is shown. Which volumetric flask has been "made up to the mark" correctly?

(A)

(B)

(C)

(D)

15.A solution of Na3PO4(aq) has a sodium ion concentration of 0.750 mol/L. What is the concentration of the sodium phosphate solution?

(A) 0.250 mol/L

(B) 0.500 mol/L

(C) 2.25 mol/L

(D) 3.00 mol/L

16.The following mass measurements were obtained by a student in the lab:

mass of filter paper and dry product ...... 3.68 g

mass of fluted filter paper before use ..... 2.18 g

mass of dry product ............................... ? g

What is the mass of the dry product?

(A) 1.5 g

(B) 1.50 g

(C) 5.86 g

(D) 5.9 g

SOLUTIONS/DILUTIONS

Part 11 Questions

2008

41.

(ii) Briefly state the steps you would use to make the NaCl(aq) solution (above) in the

lab.

Sample 2009

41.

41 f. Calcium ion, Ca2+, is one of the ions in human blood. Using the solubility

table, determine which substances below, if swallowed, would result in a

significant decrease in calcium ion concentration in the blood. Give reasons

for choices in the space provided.

2009

41. d. (i)Determine the volume of a 2.00 mol/L solution required to make 250.0 mL of a 0.200 mol/L solution.

41 f. A student discovered a bottle which contains a clear colorless solution. The label on the bottle, which was partially removed, read “_______ nitrate”. The student tested two samples of the solution to determine the compound.

In test tube A the student added a few drops of and a precipitate formed.

In test tube B the student added a few drops of and a precipitate formed.

What are two possible names for the solution in the bottle? Explain.

2010 none

2011

41 (d)Calculate the theoretical yield of hydrogen gas, in grams, produced

when 20.0 g of calcium metal, Ca(s), reacts with 1.50 L of 0.500 mol/L

hydrochloric acid, HCl(aq), according to the reaction below.

Ca(s) + 2 HCl(aq) → H2(g) + CaCl2(aq)

41. (e)Calculate the volume of a 0.300 mol/L solution, Mg(ClO3)2(aq), that contains 75.0 g of magnesium chlorate solute.

41. (f)Three beakers are labeled A, B, and C. Each beaker contains one of the

solutions below:

CaI2(aq), NH3(aq), NaClO4(aq)

Each beaker’s solution is tested for electrical conductivity and reaction with a

solution of silver ions. The results are tabulated below:

Electrical Conductivity

Reaction with Ag+(aq)

Beaker A

No

No precipitate

Beaker B

Yes

Precipitate forms

Beaker C

Yes

No precipitate

Identify the chemical formula of the solution in each beaker. Briefly explain

your choices.

2010

41. (d) A student prepared 1.500 L solution of KMnO4.

(i) Using the data in the table, calculate the concentration of the solution.

Mass of KMnO4 + vial

15.6 g

Mass of empty vial

10.4g

41. (e)Calcium chloride, CaCl2, dissociates to form calcium and chloride ions.

CaCl2 (aq) Ca2+ (aq) + 2Cl- (aq)

Calculate the mass of CaCl2 required to produce 4.0 L of solution that has a chloride ion concentration of 0.26 mol/L.

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