Top of Form1. What is the pH of a buffer that results when 33 g NaHCO3 is mixed with 100.0 mL of 2.50 M NaOH and diluted with water to 250 mL? (Ka for HCO3- = 4.8 10-11)(Points : 10)

8.20 10.07 10.12 10.32 10.56

2. What is the pH of an aqueous solution of 0.30 M HF and 0.15 M F-? (Ka of HF = 7.2 10-4)(Points : 10)

1.83 2.84 3.14 3.44 10.86

3. Which of the following mathematical expressions is the Henderson-Hasselbalch equation?(Points : 10)

pKa = pH + log pH = pKa + log pH = pKa + log pKa = pH - log pH = pKa + log

4. The Ksp of CaSO4 is 4.9 10-5 at 25 C. What is the concentration of Ca2+ in a saturated solution of CaSO4?(Points : 10)

2.4 10-9 M 2.5 10-5 M 4.9 10-5 M 7.0 10-3 M 3.7 10-2 M

5. What is the pH of the buffer that results when 12.5 g of NaH2PO4 and 22.0 g Na2HPO4 are mixed and diluted with water to 0.500 L? (The acid dissociation constants for phosphoric acid are Ka1 = 7.5 10-3, Ka2 = 6.2 10-8, and Ka3 = 3.6 10-13)(Points : 10)

2.30 7.04 7.38 12.27 12.62

6. Which of the following combinations would be the best to buffer an aqueous solution at a pH of 5.0?(Points : 10)

H3PO4 and H2PO4-, Ka1 = 7.5 10-3 HNO2 and NO2-, Ka = 4.5 10-4 CH3CO2H and CH3COO-, Ka = 1.8 10-5 H2PO4- and HPO42-, Ka2 = 6.2 10-8 NH4+ and NH3, Ka = 5.7 10-10

7. A 50.0 mL sample of vinegar is titrated with 0.774 M NaOH(aq). If the titration requires 41.6 mL of NaOH(aq), what is the concentration of acetic acid in the vinegar?(Points : 10)

0.0921 M 0.429 M 0.644 M 0.930 M 0.967 M

8. Which of the following equations is the solubility product for magnesium iodate, Mg(IO3)2?(Points : 10)

Ksp = [Mg2+][I-]2[O2-]6 Ksp = [Mg2+][I-]2[3O2-]2 Ksp = [Mg2+] Ksp = [Mg2+]2 Ksp = [Mg2+]2

9. What color change is exhibited by phenolphthalein during a titration of aqueous acetic acid with aqueous sodium hydroxide?(Points : 10)

colorless to pink pink to colorless green to yellow yellow to blue blue to yellow

10. Which of the following combinations would be best to buffer an aqueous solution at a pH of 2.0?(Points : 10)

H3PO4 and H2PO4-, Ka1 = 7.5 10-3 HNO2 and NO2-, Ka = 4.5 10-4 CH3CO2H and CH3COO-, Ka = 1.8 10-5 H2PO4- and HPO42-, Ka2 = 6.2 10-8 NH4+ and NH3, Ka = 5.7 10-10

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