1. Determine the Percentage of Oxygen by Mass in C12H22O11

CH 115 Fall 2014Mock Exam 3

Multiple Choice

1. Determine the percentage of oxygen by mass in C12H22O11.

a). 24.4%

b). 42.1%

c). 51.5%

d). 55.2%

2. A 100-gram sample of Na2SiO3 contains how many moles of sodium ions?

a). 0.82 moles

b). 1.64 moles

c). 0.41 moles

d). 1.22 x 104 moles

3. How many atoms of iron are present in 31.75 grams of the metal?

a). 3.42 x 1023

b). 0.568

c). 5.68 x 1022

d). 1.91 x 1021

4. Iron reacts with oxygen to form iron (III) oxide. Which of the reactions below is correct and properly balanced?

a). Fe (s) + O ® FeO (s)

b). 3 Fe (s) + O2 ® Fe3O2 (s)

c). Fe (s) + O2 ® FeO2

d). 4 Fe (s) + 3 O2 (g) ® 2 Fe2O3 (s)

5. How many grams of carbon dioxide are produced from the complete combustion of 10.0 grams of butane?

a). 30.3 g

b). 15.2 g

c). 7.59 g

d). 0.34 g

6. Lithium reacts violently with water to produce lithium hydroxide and hydrogen gas. If a reaction vessel contains 10.0 grams of lithium and 15.0 grams of water, how many grams of lithium hydroxide shall be produced?

a). 39.9 grams

b). 34.5 grams

c). 27.2 grams

d). 19.9 grams

7. Which of the following is a strong electrolyte in aqueous solution?

a). AgNO3

b). CaCl2

c). Li2SO4

d). all of these

e). none of these

8. In the following oxidation-reduction reaction, which is the reducing agent?

Rb (s) + Cu2+ (aq) ® Rb+ (aq) + Cu (s)

a). Rb (s)

b). Cu2+ (aq)

c). Rb+ (aq)

d). Cu (s)

9. Which of the following species is not present in the net ionic equation for the reaction between acetic acid and sodium hydroxide?

a). CH3COOH (aq)

b). Na+ (aq)

c). H2O (l)

d). CH3COO- (aq)

10. A 5.95-gram sample of silver nitrate is reacted with barium chloride to give 3.36 grams of silver chloride. What is the percent yield of silver chloride?

a). 44.6%

b). 33.5%

c). 66.9%

d). 56.5%

e). 100%

11. How many grams of sodium chloride should be dissolved in 100 mL of water to create a solution that is 0.845 M?

a). 0.0845 grams

b). 4.94 x 103 grams

c). 4.94 grams

d). 5.78 grams

12. 27.8 mL of sodium hydroxide were added to 34.2 mL of a 0.329 M solution of nitric acid to reach the equivalence point of a titration. What is the molarity of the solution of sodium hydroxide?

a). 0.405 M

b). 0.267 M

c). 0.020 M

d). 0.329 M

13. A molecule composed of C, H, and O is combusted in oxygen gas. Combustion analysis of 1.750 grams of this molecule yields 1.695 grams of H2O and 4.142 grams of CO2. What is the simplest formula for this molecule?

a). C7H14O2

b). C7H7O4

c). C8H10O3

d). C8H16O

e). C9H6O

14. A carbon compound has an empirical formula of CH2O and had an approximate molecular weight of 117. What is its molecular formula?

a). C4H4O4

b). C8H4O8

c). C4H8O4

d). C3.9H7.8O3.9

15. What is the molar mass of a gas in g/mol if 1.00 L of the gas at 0 oC and 1.00 atm of pressure has a mass of 2.86 grams?

a). 22.4

b). 64.1

c). 58.7

d). 69.9

e). 80.2

16. If the pressure of a sample of gas is doubled and the temperature is also doubled, by what factor does the volume of the sample change?

a). 1/4

b). 4

c). no change

d). 2

17. Which of the following conditions would allow a gas to behave most ideally?

a). Low pressure, high temperature

b). High pressure, low temperature

c). Low pressure, low temperature

d). High pressure, high temperature

18. What is the value for ΔH for the following reaction?
CS 2 (l) + 3 O 2 (g) → CO 2 (g) + 2 SO 2 (g)

Given these reactions:
C(s) + O 2 (g) → CO 2 (g); ΔH f = -393.5 kJ/mol
S(s) + O 2 (g) → SO 2 (g); ΔH f = -296.8 kJ/mol
C(s) + 2 S(s) → CS 2 (l); ΔH f = 87.9 kJ/mol

a). -1075.0 kJ/mol

b). -1468.5 kJ/mol

c). -602.4 kJ/mol

d). -1204.8 kJ/mol

19. Calculate the standard enthalpy of reaction for the combustion of propane (C3H8). Standard heats of formation: C3H8 = -92.30 kJ/mol, CO2 = -393.5 kJ/mol, H2O = -285.5 kJ/mol.

a). -863.6 kJ/mol

b). -2230.2 kJ/mol

c). 2414.8 kJ/mol

d). 908.7 kJ/mol

20. Calculate the amount of heat required to convert 200 grams of water at 15 oC to water at 120 oC. The heat of vaporization of water is 2.26 kJ/g and the heat of fusion is 0.334 kJ/g.

a). 432.5 kJ

b). 8647 kJ

c). 539.9 kJ

d). 675.0 kJ

21. Lead, water, sulfur, and arsenic have specific heats of 0.128, 4.18, 0.706, and 0.329 J/goC, respectively. Which of these would require the smallest amount of heat to increase its temperature by 10oC?

a). Lead

b). Water

c). Sulfur

d). Arsenic

22. What is the final temperature when 150 grams of water at 90oC is added to 100 grams of water at 30oC?

a). 60oC

b). 51oC

c). 66oC

d). 120oC

23. Which of the following can be classified as a precipitation reaction?

a). Mixing sodium nitrate with aluminum acetate

b). Mixing lead nitrate with sodium sulfate

c). Mixing sodium chloride with magnesium nitrate

d). Mixing barium bromide with potassium iodide

Short Answer

24. Draw and explain the difference between dissolving hydrochloric acid and acetic acid in water.

Hydrochloric acid is a strong acid, which means it is a strong electrolyte. It will completely dissociate into its component ions when dissolved in water. Acetic acid is a weak acid, which means that it is a weak electrolyte. It will only partially dissociate in water – some of it will break apart into its ions and some will stay together in a compound.