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Name ________________________
AP Chemistry By Satellite
John I. Gelder
Exam II
October 11, 1990

INSTRUCTIONS:

1. This examination consists of a total of 11 different pages. The last three pages include a periodic table and some useful information, a table of standard heats of formation and an activity series. All work should be done in this booklet.

2. PRINT your name, high school, teaching partner's name and the date now in the space at the top of this sheet. DO NOT SEPARATE THESE PAGES.

3. Answer all questions that you can and whenever called for show your work clearly. Your method of solving problems should pattern the approach used in lecture. You do not have to show your work for the multiple choice or short answer questions.

4. No credit will be awarded if your work is not shown in problems 2 - 7.

5. Point values are shown next to the problem number.

6. Budget your time for each of the questions. Some problems may have a low point value yet be very challenging. If you do not recognize the solution to a question quickly, skip it, and return to the question after completing the easier problems.

7. Look through the exam before beginning; plan your work; then begin.

8. Relax and do well.

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(9) 1. Write the chemical formula(s) of the product(s) and balance the following reactions which were demonstrated in lecture. Identify all products phases as either (g)as, (l)iquid, (s)olid or (aq)ueous.

(9) 2. The overall equation for the preparation of potassium perchlorate, a powerful explosive, is,

Calculate the mass of KClO₄ which can be produced when 100. g of KOH are reacted with 100. g of Cl₂. (Molar mass of Cl₂ is 70.9 g and KOH is 56.1 g.)

Very similar to Exercise 17d in Chapter 3:

(8) 3. Calculate the DHº_rxn for the combustion of glycine, an important amino acid,

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(10) 4. Calculate the concentration of a phosphoric acid, H₃PO₄, solution if 24.00 mL is neutralized by 12.00 mL of a 0.600 M NaOH solution.

Very similar to Exercise 22d in Chapter 3:

Important neutraization reaction,

(8) 5. Using the following standard enthalpy of reaction data,

to calculate DHº for the following reaction

Very similar to Exercise 19c in Chapter 4:

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(8) Solve ONE of the two problems in this part. (A second problem will not be scored.) Show all important calculations and provide a brief explanation of how the solution is prepared.

6. Describe how you would prepare the following solution,

a) 250.00 mL of 0.450 M NaNO₃ from NaNO₃(s) and water

Very similar to Exercise 21e in Chapter 3:

b) 1200 mL of 2.50 M H₂SO₄ from 9.00 M H₂SO₄

Very similar to Exercise 21f in Chapter 3:

Measure 333 mL of 9.00 M H₂SO₄ and add the solution to
approximately 600 mL of distilled water. Remember always add acid to water when diluting a concentrated acid or base solution. Then add enough water to the diluted solution to obtain a final volume of 1200 mL of solution.

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(10) Solve ONE of the two problems in this part. (A second problem will not be scored.)

7. A 50.00 g sample of 0.600 M NaOH(aq) at 22.00 ºC is added to a coffee-cup calorimeter containing 50.00 g of 0.600 M HCl(aq) at 22.00 ºC. If the heat capacity of the calorimeter is 50.0 J/ºC and the specific heat of the solution is the same as that of water (4.184 J/ºC) and the final temperature of the solution in the calorimeter is 25.40 ºC, calculate the heat released in the reaction.

Very similar to Exercise 9c in Chapter 4:

8. Glucose, C₆H₁₂O₆ reacts with oxygen according to the reaction,

Calculate the heat produced per mole of glucose when 1.80 g of C₆H₁₂O₆ are combused with excess oxygen in a bomb calorimeter containing 3.50 kg of water. The temperature change measured is 1.68 ºC. The heat capacity of the calorimeter is 2050 J/ºC .

Identical to Exercise 11b in Chapter 4:

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(12) 9. For each of the following reactions use the activity series to predict the products. If no reaction occurs write NR. Balance the equations and identify the product phases as either (g)as, (l)iquid, (s)olid or (aq)ueous. (Note: Points will be removed if the phases of the products are not provided.)

Very similar to Exercise 9a in Chapter 5:

(5) 10. Compare and contrast the techniques of filtering and decanting. What factors must be considered in determining which of these two techniques is the most appropriate for separating a given mixture?

Both filtering and decanting are used to separate heterogeneous mixtures. If the mixture contains a dense solid in a liquid, decanting may be adequate. If the mixture contains a suspended solid, filtering must be used to separate the mixture.

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Multiple Choice:

Print the letter (A, B, C, D, E) which corresponds to the answer selected.

11. B 12. D 13. E 14. B

15. A 16. A 17. A

ONLY THE ANSWERS IN THE AREA ABOVE WILL BE GRADED. Select the most correct answer for each question. Each question is worth 3 points.

11. Which of the following reactions is not exothermic?

12. The addition of 3.31 kJ of heat to a 300. g sample of mercury at 19.0 ºC caused the temperature to rise to 99.0 ºC. What is the specific heat of mercury?

13. Which of the following equations is an example of a standard formation reaction?

14. For which of the following reactions is DE = DH?

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15. Given the reaction,

If 25.2 g of FeSO₄, 11.6 g of K₂CrO₄, and 23.5 g H₂SO₄ are mixed together, which reactant is the limiting reagent? (Molar masses:
FeSO₄ = 152 g;
K₂CrO₄ = 194 g;
H₂SO₄ = 98.0 g)

A) FeSO₄
B) K₂CrO₄
C) H₂SO₄
D) K₂CrO₄ and H₂SO₄
E) not enough information

16. Which of the separation techniques listed below would be the most efficient in separating a mixture of dyes in a single drop of sample?

A) paper chromatography
B) decantation
C) evaporation
D) filtering
E) column chromatography

17. A pure sample of an oxide of mercury with a mass of 0.856 g was completely decomposed to its elements by heating, producing 1.976 x 10^-3 moles of O₂. What is the likely formula of this oxide?

A) HgO
B) Hg₂O
C) HgO₂
D) Hg₂O₃
E) Hg₃O₂