Exam 3--S/98

Chemistry 122S
Summer 1998
Oregon State University
Exam 3
August 6, 1998
Dr. Richard Nafshun

Name _______________________________________ Score ___________ / 100

Possibly useful information:

 [Periodic Table Here]

Objective: Identify Strong, Weak, and Non Electrolytes--5 Problems, 2 Points Each

For problems 1-5, circle or box the correct the best description.

For example,

Sucrose is a: strong-electrolyte weak-electrolyte non-electrolyte.

1. NH₃ is a: strong-electrolyte weak-electrolyte non-electrolyte.

2. HCl is a: strong-electrolyte weak-electrolyte non-electrolyte.

3. CH₄ is a: strong-electrolyte weak-electrolyte non-electrolyte.

4. CH₃COOH is a: strong-electrolyte weak-electrolyte non-electrolyte.

5. CH₃CH₂OH is a: strong-electrolyte weak-electrolyte non-electrolyte.

Objective: Identify Acids and Bases--5 Problems, 2 Points Each

6. List a strong acid: ___________________________________________.

7. List a weak acid: ___________________________________________.

8. List a strong base: ___________________________________________.

9. List a weak base: ___________________________________________.

10. List a compound that is neither an acid nor a base: _____________________.

Objective: Determine Oxidation Numbers--5 Points

11. The oxidation number (oxidation state) of Mo in LiMoO₃ is _____________.

(Include the sign)

Objective: Discuss Redox Reactions--5 Problems, 2 Points Each

Problems 12-16 refer to the following balanced reaction:

Mg (s) + CuSO₄ (aq) ------> MgSO₄ (aq) + Cu (s)

12. The reducing agent is _____________________________.

13. The oxidizing agent is _____________________________.

14. The species being reduced is _____________________________.

15. The species being oxidized is _____________________________.

16. The species gaining electrons is _____________________________.

Objective: Calculate the Concentration of a Reagent Based on Titration Data--10 Points

17. A student titrated 50.00 mL of an HCl solution of unknown concentration. She added 38.25 mL of 0.09872 M sodium hydroxide to reach the equivalence point. Determine the concentration of the HCl solution.

 

Objective: Calculate the Freezing Point Depression--10 Points

18. A student places 1445 grams of sucrose, C₁₂H₂₂O₁₁ (FW = 342.3), in 2.000 kg of water. Calculate the freezing point of the solution.

 

Objective: Discuss Freezing Point Depression--10 Points

19. When sucrose is placed in water, why is the freezing point of the solution less than 0 ° C?

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Objective: Discuss Non-Ideal Solutions--10 Points

20. A student mixes 50.00 mL of water and 50.00 mL of ethanol. What is the approximate volume of the mixture? Why?

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Objective: Calculate Osmotic Pressure--10 Points

21. A student places 3.445 grams of sucrose, C₁₂H₂₂O₁₁ (FW = 342.3), in 1.000 L of water at 20 ° C. Calculate the osmotic pressure of the solution.

 

 

Objective: Discuss the Effect of Pressure on the Solubility of Gases--10 Points

22. A student obtains two cans of a popular carbonated soft drink. She opens one can and not the second. Which beverage contains the greatest concentration of carbon dioxide? Why?

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Objective: Discuss the Vapor Pressure of Solutions--5 Points

23. At 1.0 atm, why is the vapor pressure of water greater at 40 ° C than at 20 ° C?

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