Chemistry 2202 Year End Review June 2011 NOTE : All Units reviewed, keep scrolling to bottom

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

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/mol4. 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

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14. What is the average atomic mass of the newly found element Nonamium (No) giventhe following percent abundances:

(A) 93.72 amu(B) 280.78 amu(C) 280.85 amu(D) 281.16 amu

16. B

17. D

2009

1. What is the isotope name of Cu2968 ?

(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, Ca (OH )2?(A) 38.00 g/mol(B) 58.10 g/mol(C) 74.10 g/mol(D) 116.20 g/mol

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4. How many calcium atoms are there in a 3.00 mol sample?(A) 4.98 × 10−24

(B) 2.01 ×1023

(C) 6.02 ×1023

(D) 1.81 ×1024

5. What is the mass of 0.300 mol of CaS O4 (molar mass = 136.15 g/mol)?(A) 2.20 ×10−3 g(B) 40.8 g(C) 48.9 g(D) 4.54 ×102 g

6. How many molecules of C6 H12O6 (molar mass = 180.18 g/mol) are present in a 5.50 g sample?(A) 5.07×10−26

(B) 3.05 ×10−2

(C) 1.84 ×1022

(D) 1.97 ×1025

12. Large deposits of gypsum, an ionic hydrate, are located in western Newfoundland. By mass, what percentage of gypsum, CaS O4 ∙2 H 2O, is water?

(A) 6.210%(B) 20.93%(C) 66.67%(D) 79.07%

14. At 25 . 0° C and 100.0 kPa, the molar volume of a gas is 24.8 L/mol. What volume would 4.85 × 1023 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?

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(A) 7.01 L(B) 14.0 L(C) 35.8 L(D) 71.8 L

20111. 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.

ANSWER 44.7 L of Cl2

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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?

Answer 5 Molecules of H2O

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, N O2(g ) 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. TREAT AMU as Grams

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 17.71 275.985Novium -280 11.60 279.859

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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 atomicmass of 62.93 amu and a relative abundance of 69.1%. The percentabundance of the other isotope is 30.9%. If the average atomic mass ofcopper is 63.55 amu, calculate the atomic mass of the other isotope.

% 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 ifthe 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 ofsodium 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

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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%

% 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.

C2H5

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

C4H10

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.

200941. 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 C2 H4. Determine the molecular formula of the compound.

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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.

Stoichiometry Part 1 Questions

2008

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

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

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10. ANS D

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 calciumcarbonate, 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

18. ANS D

2009

7. Given the balanced chemical equation: 4 Ag(s)+2 H2 S(g )+O 2(g)→2 Ag2 S(s)+2 H 2O(g)

what volume of H 2O(g ) should be produced at STP by the reaction of 0.208 mol of Ag(s ) with sufficient quantities of H2 S(g ) and O2( g)?(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:

2 AgN O3(aq)+Cu(s )→ 2 Ag( s)+Cu ( N O3 )2(aq)

If 5 mol of AgN O3 (aq) is mixed with 3 mol of Cu(s ), which is the limiting reagent?(A) Ag(s )

(B) AgN O3 (aq)

(C) Cu(s )

(D) Cu ( N O3 )2 (aq)

9. How many moles of C O2 (g) are produced by the complete combustion of 3.5 mol of C6 H 14 (l )?

2 C6 H 14(l)+19 O2( g)→ 12C O2(g)+14 H 2O(g)

(A) 3.5 mol

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(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%

Stoichiometry Part 11 Questions

200841. (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 ofAl(s) expected, in grams. ANS 0.647 g

(ii) If the experiment produced 0.515 g of Al(s), calculate the percent yield for thereaction. ANS 79.7 %

41. (f) An unknown alkaline earth metal (Group IIA) "M" reacts with a solution of sodiumfluoride, 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 theidentity of the metal "M"? Show all workings. ANS Ca

Sample 2009

41.

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41. e

2009

41. e. (i) A student reacts 50.0 g of SiO2(s )with excess H F(aq). Calculate the theoretical yield of H 2O(l) in grams.

SiO2(s )+4 H F(aq)→ Si F4(g)+2 H 2O(l)

(ii) If the actual yield of H 2O(l) produced in part (i) was 24.6 g, determine the percent yield.

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2010

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/DILUTIONSPart 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 25EC. 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

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(D) 6.00L

Sample 2009ANSWER 7 (A), 8 (C)

ANSWER 11 (C)

ANSWER 13 (C)

ANSWER 15 (B)

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

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11. What is the concentration of 0.250L solution that contains 2.50 g of Ca3 ( P O4 )2 (molar mass = 310.18 g/mol)?(A) 2.02 ×10−3mol/L(B) 3.22 ×10−2mol/L(C) 31.0 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) 2.50 ×10−2 g(B) 1.00 g(C) 16.0 g(D) 1.00 ×102 g

14. At 25 . 0° C and 100.0 kPa, the molar volume of a gas is 24.8 L/mol. What volume would 4.85 × 1023 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, K3 PO 4(s )?

(A) K 3 PO 4(s )→ 3K (aq)+ ¿+P O4 (aq)

3−¿¿ ¿

(B) K 3 PO 4(s )→ K3(aq)+¿+PO 4(aq)

3−¿¿ ¿

(C) K 3 PO 4(s )→ 3K (aq)+ ¿+P(aq)

3−¿+4O( aq)2−¿¿¿ ¿

(D) K 3 PO 4(s )→ K(aq)3+¿+ PO4( aq)

3−¿¿¿

16. Which has low solubility in water?(A) Ba (OH )2(B) CaS O4

(C) Cu(N O3)2

(D) MgCl2

17. What is the concentration of nitrate ions in a 0.60 mol/L solution of lead(IV) nitrate, Pb ( N O3 )4(aq )?(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

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(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) + SO4

2- (aq)

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

2- (aq)

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

2- (aq)

SOLUTIONS/DILUTIONSPart 11 Questions

2008

41.

ANS 25.0 mL or 0.0250 L

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

ANS 1. Pipette 25.0 mL of NaCl(aq) from the beaker.

2. Drain the solution into the 500.0 mL volumetric flask.

3. Add water up to the mark with the eyedropper.

4. Cap the flask and invert several times to ensure a homogenous mixture is created.

Sample 2009

41.

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41 f. Calcium ion, Ca2+, is one of the ions in human blood. Using the solubilitytable, determine which substances below, if swallowed, would result in asignificant decrease in calcium ion concentration in the blood. Give reasonsfor choices in the space provided.

ANSWERsodium acetate No will not form a precipitate

sodium chloride No will not form a precipitate

sodium nitrate No will not form a precipitate

sodium sulfate No will not form a precipitate

2009

41. d. (i) Determine the volume of a 2.00 mol/L KN O3 (aq) solution required to make 250.0 mL of a 0.200 mol/L KN O3 (aq) 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 NaCl(aq ) and a precipitate formed.

In test tube B the student added a few drops of Na2 SO4 (aq) and a precipitate formed.

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

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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.

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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Mass of KMnO4 + vial 15.6 g

Mass of empty vial 10.4g