Chemistry 050-03

This is a sample Final Exam given in chem 050 in 1988 at the University of Idaho

Problem Set #3

Due: November 29, 1988

SHOW ALL WORK using DIMENSIONAL ANALYSIS SET UPS on the problems.

1. (10 pts) If 15.3 g of Fe2O3 produces 10.0 g of Fe, according to the equation

Fe2O3 + 3 CO --> 2 Fe + CO2,

What is the percent yield of the reaction?

2. (5 pts) In the reaction

2 AgNO3 + K2S --> Ag2S + 2 KNO3,

calculate the grams of K2S needed if a 8.0% excess is supplied in a reaction with 84.6 miligrams AgNO3.

3. (5 pts) A 0.551 gram sample composed of Ag2S and inert matter yielded 0.438 grams pure AgCl. Calculate the percent Ag2S in the original sample.

4. (10 pts) For the sequence of reactions

FeCr2O4 + 8 HCl --> FeCl2 + 2 CrCl3 + 4 H2O

CrCl3 + 4 NaOH --> 3 NaCl + NaCr(OH)4

2 NaCr(OH)4 + 3 H2O2 + 2 NaOH --> 2 Na2CrO4 + 8 H2O

calculate the pounds of FeCr2O4 consumed if 138 pounds of Na2CrO4 are produced.

5. (10 pts) A solution is prepared by mixing 24.6 grams H2SO4 with 48.4 grams H2O. The resulting solution has a density of 1.32 g/mL.

a) Calculate the molarity of the solution.

b) Calculate the molality of the solution.

6. (10 pts) a) Calculate the milliliters of 0.200 M Mg(OH)2 solution needed to react with 32.7 mL of 0.156 M HCl solution by the reaction

Mg(OH)2 + 2 HCl --> MgCl2 + 2 H2O

b) Calculate the molarity of an HNO3 solution if 16.4 mL were needed to react with 0.124 grams of (NH4)2CO3 by the reaction:

2 HNO3 + (NH4)2CO3 --> H2O + CO2 + 2 NH4NO3

7. (10 pts) a) Calculate the milliliters of 1.00 M CdCl2 solution needed to prepare 756 mL of 0.225 M solution.

b) Calculate the molarity of a solution prepared by mixing 845 mL 5.00 M HBr soluion with 325 mL 1.5 M HBr solution.

8. (5 pts) Calculate the mL of 23.4% Cu(NO3)2 solution having a density of 1.21 g/mL needed to completely react with 34.9 grams of KI in the reaction

2 Cu(NO3)2 + 5 KI --> 2 CuI + KI3 + 4 KNO3

9. (5 pts) Calculate the milliliters of 98.0% H2SO4 solution having a density of 1.84 g/mL needed to make 275 mL of 40.0% H2SO4 solution having a density of 1.40 g/mL.

10. (10pts) Using logarithm tables, calculate the answer for the following expression. (Show all calculations).

2.13 x 105)(46.3 x 10-3)/(0.317)(8.641 x 102)

11. (10 pts) Using logarithms, evaluate the following. (Show all work.)

a) (6561)1/3

b) (0.0003181)5

12. a) (5 pts) Using logarithms, find the pH of a solution that has [OH-] = 6.89 x 10-10 molar.

b) (5 pts) Using logarithms, calculate the p[OH] of a solution where 480.3 mL of the solution contain 5.66 x 10-6 mols of hydrogen ion. (Show all work.)