Directions. The exam is closed book - no use of any written reference materials or discussion with classmates is permitted. Your eyes should remain on your own exam paper at all times.
You have 65-minutes in which to complete work on all four problems. If you have any questions, please raise your hand and I will be glad to answer your questions if I can. Good luck!
1. (25 points - 1 point each pH cell, 2 points each formula and acid/base/salt cell) Name FIVE of the SIX compounds below and in the space provided write the correct formula, identify the acid/base/salt nature of the compound and indicate whether an aqueous solution of each would be acidic, basic, or neutral in pH. Please be sure to indicate for acids and bases whether they are strong or weak acids/bases. For salts indicate whether they are salts of weak acids, salts of weak bases, salts of strong acids and strong bases, salts of weak acids and weak bases. Please clearly indicate which five compounds you wish graded. If you do not indicate which five compounds you wish graded, I will grade the first five compounds only.
Compound
Formula
Acid/Base/Salt
Aqueous pH
Nitric acid
Silver nitrate
Sodium chloride
Ammonia
Sodium acetate
Ammonium chloride
2. (25 points) 2.5 mL of 0.0054 M magnesium chloride are mixed with 5.2 mL of 0.0105 M silver nitrate. How many ppm of silver chloride (FW 143.321) are produced in the reaction?
3. (20 points) The chloride in a 1.50 g sample containing calcium chloride (FW 110.99) and sodium chloride (FW 58.44) is converted to silver chloride (FW 143.321) by the addition of excess aqueous silver nitrate. The washed and dried silver chloride precipitate is found to weigh 3.76 g. Calculate the percent of calcium chloride and sodium chloride in the original sample.
a. (5 points) Write an expression for the number of grams of silver chloride produced from the calcium chloride in the original sample.
b. (5 points) Write an expression for the number of grams of silver chloride produced from the sodium chloride in the original sample.
c. (5 points) Calculate the number of grams of calcium chloride and the number of grams of sodium chloride in the original sample.
4. (30 points) Calculate the pH and pOH of the solution prepared by mixing 35 mL of a strong acid pH 2.5 and 25 mL of a strong base pH 11.00.
a. (5 points) What is the chemical reaction involved in this problem?
b. (5 points) How many moles of the strong acid are used in this reaction?
c. (5 points) How many moles of the strong base are used in this reaction?
d. (5 points) Which reagent is the limiting reagent in the reaction?
e. (5 points) What is the total volume of the resulting solution?
f. (5 points) What is the pH and the pOH of the resulting solution?