Question 1

Which of the following best describes a buffer solution?

Accepted Answer

A solution that resists changes in pH when small amounts of acid or base are added.

Question 2

Which equation is used to calculate the pH of a buffer solution?

Accepted Answer

$$\mathrm{pH} = \mathrm{p}K_\mathrm{a} + \log \left( \frac{[	ext{base}]}{[	ext{acid}]} ight)$$

Question 3

A buffer is made by mixing acetic acid and sodium acetate. What happens to the pH when a small amount of HCl is added?

Accepted Answer

The pH decreases slightly.

Question 4

Which of the following best explains why biological systems require buffers?

Accepted Answer

Because enzymes and cellular processes function only within narrow pH ranges.

Question 5

Given $$K_\mathrm{sp}$$ for $$\mathrm{AgCl} is$$ $$1.8 	imes 10$$^{-10}$$, what is the molar solubility of $$\mathrm{AgCl}$$ in pure water?

Accepted Answer

$$1.3 	imes 10$$^{-5}$$ M

Question 6

Which of the following will decrease the solubility of $$\mathrm{CaF}_2 in $$water?

Accepted Answer

Adding $$\mathrm{NaF} to $$the solution.

Question 7

What is the effect of adding a common ion to a saturated solution at equilibrium?

Accepted Answer

It decreases the solubility of the salt.

Question 8

Which of the following best describes the relationship between $$Q$$ and $$K_\mathrm{sp} in $$predicting precipitation?

Accepted Answer

If $$Q \u003e K_\mathrm{sp}$$, precipitation will occur.

Question 9

During a titration of a weak acid with a strong base, at what point does $$\mathrm{pH} = \mathrm{p}K_\mathrm{a}$$?

Accepted Answer

At the half-equivalence point.

Question 10

Which of the following is true about the equivalence point in a strong acid-strong base titration?

Accepted Answer

The pH is always 7 at the equivalence point.

Question 11

How does the formation of a complex ion affect the solubility of a sparingly soluble salt?

Accepted Answer

It increases the solubility.

Question 12

Which of the following is the correct expression for the solubility product constant ($$K_\mathrm{sp}) $$for $$\mathrm{BaSO}_4$$?

Accepted Answer

$$K_\mathrm{sp} = [\mathrm{Ba}^{2+}][\mathrm{SO}_4$$^{2-}$$]$$

Question 13

A buffer is prepared with $$0.10 M $$acetic acid and $$0.10 M $$sodium acetate. What is the pH if $$\mathrm{p}K_\mathrm{a}$$ for acetic acid is $$4.76$$?

Accepted Answer

$$4.76$$

Question 14

Which of the following best describes selective precipitation?

Accepted Answer

A process used to separate ions in a mixture by adding a reagent that precipitates one ion but not others.

Question 15

Which of the following would best increase the buffer capacity of a solution?

Accepted Answer

Increasing the concentrations of both the weak acid and its conjugate base.

Question 16

If $$K_\mathrm{sp}$$ for $$\mathrm{PbCl}_2 is$$ $$1.7 	imes 10$$^{-5}$$, what is the molar solubility of $$\mathrm{PbCl}_2$$ in pure water?

Accepted Answer

Aqueous Ionic Equilibrium: Buffers, Titrations, and Solubility

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