CH 115 Fall 2015 Mock 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 molesb). 1.64 molesc). 0.41 molesd). 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). 0.568c). 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 gb). 15.2 gc). 7.59 gd). 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 will be produced?a). 39.9 gramsb). 34.5 gramsc). 27.2 gramsd). 19.9 grams

7. Which of the following is a strong electrolyte in aqueous solution?a). AgNO3

b). CaCl2

c). Li2SO4

CH 115 Fall 2015 Mock Exam 3

d). all of thesee). 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. 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). C8H16Oe). C9H6O

12. 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

13. Which of the following can be classified as a precipitation reaction?a). Mixing sodium nitrate with aluminum acetateb). Mixing lead nitrate with sodium sulfatec). Mixing sodium chloride with magnesium nitrated). Mixing barium bromide with potassium iodide

CH 115 Fall 2015 Mock Exam 3

14. Which of the following will react as written? a). Sn (s) + Fe2+ (aq) Sn2+ (aq) + Fe (s)b). Mg (s) + Cu2+ (aq) Mg2+ (aq) + Cu (s)c). Fe (s) + Al3+ (aq) Fe3+ (aq) + Al (s)d). Pb (s) + Zn2+ (aq) Pb2+ (aq) + Zn (s)

15. What is the oxidation state of carbon in C2O42-?

a). +Ib). –IIc). +IIId). +IV

16. 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 gramsb). 4.94 x 103 gramsc). 4.94 gramsd). 5.78 grams

17. Determine the new concentration of a solution of nitric acid if 175 mL of 1.6 M nitric acid is diluted to 1.0 L. a). 280 Mb). 9.14 Mc). 0.009 Md). 0.28 M

Short Answer

18. 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.

CH 115 Fall 2015 Mock Exam 3

19. For the following: predict the products, write the net ionic equation, and identify the type of reaction. a). Aqueous sodium carbonate is mixed with aqueous hydrobromic acidNa2CO3 (aq) + 2 HBr (aq) CO2 (g) + H2O (l) + 2 NaBr (aq) Gas-forming reactionNET: CO3

2- (aq) + 2 H+ (aq) CO2 (g) + H2O (l) b). Aqueous solutions of barium nitrate and potassium sulfate are mixed Ba(NO3)2 (aq) + K2SO4 (aq) BaSO4 (s) + 2 KNO3 (aq) Precipitation reactionNET: Ba2+ (aq) + SO4

2- (aq) BaSO4 (s)