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Your Name: ____________________________________ |
Fall 2010 |
1. (Problem 2-5 in the Davis & Masten text) A solution of sodium bicarbonate is prepared by adding 45.00 g of sodium bicarbonate to a 1.00 L volumetric flask and adding distilled water until it reaches the 1.00 L mark. What is the concentration of sodium bicarbonate in units of (a) milligrams per liter, (b) molarity, (c) normality, and (d) milligrams per liter as CaCO3? Show your work.
2. (Problem 2-6 in the D&M text; with one correction) Balance the following 5 chemical equations:
a. CaCl2 + Na2CO3
= CaCO3 + NaCl
b. C6H12O6 + O2 = CO2 + H2O
c. NO2
+ H2O = HNO3 + NO
d. C4H10
+ O2 = CO2 + H2O
e. Al(OH)3
= Al3+ + OH-
3. You've just prepared a solution by dissolving 20 mg sodium sulfide (Na2S), and 30 mg potassium sulfate dihydrate (K2SO42H2O) in 1 Liter of distilled water.
a) What is the molar concentration of sodium sulfide in this solution?
b) What is the equivalent concentration of sodium sulfide in this solution?
c) What is the molar concentration of potassium in this solution?
d) What is the concentration of total sulfur in this solution in mg/L?
e) What is the concentration of reduced sulfur (i.e., S(-II)) in this solution in mg/L?
f) What is the theoretical TDS of this solution in mg/L?
4. (Problem 2-12 in the D&M text) If 200 mg of HCl is added to water to achieve a final volume of 1.00 L, what is the final pH?
5. What amount (mass, in mg) of NaOH (a strong base), would be required to neutralize the acid in Problem 2-12? (see Problem 2-29 & Example 2-11 in D&M).
6. (Problem 2-15 in the D&M text plus an additional question) The concentration of a chemical degrades in water according to first-order kinetics. The degradation constant is 0.2 day-1. If the initial concentration is 100.0 mg/L, (a) how many days are required for the concentration to reach 0.14 mg/L? Also (b) calculate the half-life (t1/2) for this decay reaction.
7. (Problem 2-28 in the D&M text) Each mole of CaF2(s) dissolved yields 1 mole of Ca2+ and 2 moles of F- (fluoride). The solubility product of calcium fluoride (CaF2) is 3x10-11 at 25C. Could a fluoride concentration of 1.0 mg/L be obtained in water that contains 200 mg/L of calcium? Yes or no? Show your work.
Assigned: 10 Sept 10
Your Name: ____________________________________
Answer Page
Fill in the boxes with the correct answer.
You will only get credit for a problem if you: (1) fill in the box with the correct answer in the units indicated, (2) your answer is legible, and (3) you attach page(s) with calculations backing up your answer.
Problem #
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1 |
a |
|
mg/L |
|
b |
|
M |
|
|
c |
|
N |
|
|
d |
|
mg/L as CaCO3 |
|
2 |
a |
1 |
CaCl2 |
|
Na2CO3 |
= |
|
CaCO3 |
|
NaCl |
|
b |
1 |
C6H12O6 |
|
O2 |
= |
|
CO2 |
|
H2O |
|
|
c |
3 |
NO2 |
|
H2O |
= |
|
HNO3 |
|
NO |
|
|
d |
2 |
C4H10 |
|
O2 |
= |
|
CO2 |
|
H2O |
|
|
e |
1 |
Al(OH)3 |
|
|
= |
|
Al3+ |
|
|
|
3 |
a |
|
mM |
|
b |
|
meq/L |
|
|
c |
|
mM |
|
|
d |
|
mg/L |
|
|
e |
|
mg/L |
|
|
f |
|
mg/L |
|
4 |
|
pH units |
|
5 |
|
mg |
|
6 |
a |
|
days |
|
b |
|
days |
|
7 |
|