CHM 2045

Exam #2 Practice Questions

Disclaimer: This is just a review for your exam, please double check the calculations.

Some useful conversions;

1. Balanced chemical equation for the aqueous reaction between Sodium phosphate and

potassium chloride is;

a) Na3PO4(aq) + KCl(aq) → K3PO4(aq) + NaCl(aq)

b) Na3PO4(aq) + KCl(aq) → K3PO4(s) + NaCl(aq)

c) Na3PO4(aq) + 3KCl(aq) → K3PO4(aq) + 3NaCl(aq)

d) Na3PO4(aq) + 3KCl(aq) → K3PO4(s) + 3NaCl(aq)

2. Predict the coefficients in the balanced chemical equation for the following reaction.

_C4H6(g) + _O2(g) → _CO2(g) + _H2O(g)

a) 1, 4, 4, 3

b) 2, 11, 8, 6

c) 2, 8, 8, 6

d) None of the above

3.

N2 + 3H2 → 2NH3

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If 2.50 moles of nitrogen gas reacted with 4.0 moles of hydrogen gas, the moles of reactants left

after the reaction.

a) N2-0, H2-1.33

b) N2-1.33, H2-0

c) N2-0, H2-1.17

d) N2-1.17, H2-0

4. A compound has the following composition; 39.97% carbon; 13.41% hydrogen; 46.62%

nitrogen. Find the empirical formula.

a) CHN

b) CH4N

c) C2H2N

d) CH2N2

5. If the compound mentioned in the previous question has a molar mass of 60.10g/mol: 39.97%

carbon; 13.41% hydrogen; 46.62% nitrogen. Find the molecular formula

a) C2H2N2

b) C4H8N2

c) C2H4N4

d) C2H8N2

6. Find the limiting reactant if 0.064 moles of Lead (II) nitrate reacted with 0.056 moles of

Sodium phosphate.

a) Lead (II) nitrate

b) Sodium phosphate

c) None of the above

d) cannot be determined.

7. What is the percentage of yield if the reaction mentioned in the previous question (Qn #4)

gave a yield of 14.98g of Lead (II) phosphate. (Lead (II) phosphate molar mass- 811.54g/mol)

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a) 75.8%

b) 84.9%

c) 56.3%

d) 86.5%

8. Find the molarity of the solution if 32.34g of Sodium chloride dissolved in 142.0mL of water.

a) 3.2M

b) 2.5M

c) 5.2M

d) 3.9M

9. The amount (in grams) of Sodium sulfate needed to make 150.0 mL of 3.5M solution.

(Sodium sulfate-142.04g/mol)

a) 65g

b) 75g

c) 82g

d) 28g

10. Find the final concentration if 25.0 ml from 4.5M NaOH solution id diluted up to 500.0 mL.

a) 0.45M

b) 2.5M

c) 0.225M

d) 2.25M

11. Find the concentration of 30.0mL of NaOH needed for the complete neutralization of

25.0mL of 2.4M H2SO4

a) 4.8M

b) 4.0M

c) 1.2M

d) 2.4M

12. Find the reactant left after the aqueous reaction between 50.0mL of 2.4 M of silver(I) nitrate

with 50.0 mL of 1.2M Copper (II) chloride.

a) Copper (II) chloride

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b) Silver (I) nitrate

c) None of the above, a complete reaction

13. The maximum amount of Silver (I) chloride can be formed in the reaction mentioned in the

previous question.

a) 6.8g

b) 8.6g

c) 17.2g

d) 2.17g

14. What is the percent of yield if the reaction yielded 7.8g of Silver (I) chloride.

a) 114.7%

b) 90.7%

c) 45.3%

d) 27.8%

15. Find the strong electrolyte from the following

a) NH4NO3

b) PbCl2

c) Fe(OH)3

d) Ca3(PO4)2

16. All of the following compounds are soluble except

a) CaCl2

b) Hg2I2

c) Na2S

d) Ba(C2H3O2)2

17. Find the oxidation state of Carbon in carbonate ion.

a) +5

b) +4

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c) -5

d) -4

18. Oxidation state of copper in reactant and product side are ___ and ____ respectively,

Cu(s) + HNO3(aq) → Cu(NO3)2(aq) + H2(g)

a) +2, +2

b) 0, +2

c) 0, 0

d) +1, +2

19. In the previous reaction reaction, the reducing and the oxidizing agents are ___ and ___

respectively.

a) NO3-, Cu

b) Cu, N

c) Cu, HNO3

d) HNO3, Cu

20. Oxidation state of sulfur in sulfate ion.

a) 0

b) +6

c) -2

d) +2