Self Quiz

Select the letter of the best answer for each of the following questions.

1. What is the molarity of the solution which contains 5.0 g of NaOH (formula weight = 40 g/mole) dissolved in water to make 200 mL of solution?

     a. 0.025 M
     b. 0.13 M
     c. 0.20 M
     d. 0.63 M
     e. 1.6 M

2. What is the weight percent of NaCl in a solution made by dissolving 20 g of NaCl (FW = 58 g/mole) in 200 mL of water?

     a. 0.16%
     b. 0.17%
     c. 9.1%
     d. 10%
     e. 17%

3. When 40.0 mL of 2.0 M NaCl (FW = 58) is diluted to 100.0 mL, what is the new concentration?

     a. 0.20 M
     b. 0.50 M
     c. 0.80 M
     d. 5.0 M
     e. need more information to answer this question

4. How many moles of NaOH (FW = 40 g/mole) are there in 50 mL of 0.30 M NaOH solution?

     a. 0.006
     b. 0.015
     c. 0.60
     d. 6
     e. 15

5. What is the species concentration of Na⁺ in a 0.50 M solution of Na₂SO₄?

     a. 0.20 M
     b. 0.25 M
     c. 0.50 M
     d. 1.0 M
     e. 2.0 M

6. How many moles of chloride ion are there in 100 mL of 0.50 M AlCl₃?

     a. 0.050
     b. 0.10
     c. 0.15
     d. 0.5
     e. 1.5

7. Which is the most appropriate concentration unit for use in colorimetry?

     a. molarity
     b. normality
     c. volume percent
     d. weight percent

8.  If the absorbance of a 0.340 M solution of a chemical is 0.18 at a particular wavelength, what is the concentration of a solution of the the same chemical that has an absorbance of 0.023 measured at the same wavelength?

a. 0.012 M
b. 0.027 M
c. 0.043 M
d. 2.7 M

Answer the following questions.

9. What is the appropriate equilibrium constant expression for this reaction?

CaCl₂(s) Ca²⁺(aq) + 2 Cl^-(aq)

10.  If the solubility of CaCl₂ is 74.5 g in 100 mL, what are the species concentrations of Ca²⁺ and Cl^- and what is the value of K_sp for CaCl₂?

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E-mail instructor: Sue Eggling