Q: A buffer solution is prepared by mixing equal concentrations of acetic acid and sodium acetate. Which equation correctly describes the pH of this buffer?

$$\text{pH} = \text{p}K_a + \log \left( \frac{[\text{A}^-]}{[\text{HA}]} \right)$$

Q: If $$K_{sp}$$ for AgCl is $$1.8 \times 10$$^{-10}$$, what is the molar solubility of AgCl in water?

$$1.3 \times 10$$^{-5}$$ \text{ M}$$

Q: A solution is prepared by mixing 30.0 mL of 3.7 × 10$$^{-3} M Sr(NO$_3$$)$$_2$$ and 25.0 mL of 0.02 M Na$$_2SO$_4. $$Will SrSO$$_4$$ precipitate? $$K_{sp} of $$SrSO$$_4$$ = $$2.8 \times 10$$^{-7}$$.

Q = $$1.8 \times 10$$^{-5}$$; Yes

Question 1

Which of the following pairs can act as a buffer solution?

Accepted Answer

0.15 M CH3CO2H + 0.20 M CH3CO2Na

Question 2

A buffer solution is prepared by mixing equal concentrations of acetic acid and sodium acetate. Which equation correctly describes the pH of this buffer?

Accepted Answer

$$	ext{pH} = 	ext{p}K_a + \log \left( \frac{[	ext{A}^-]}{[	ext{HA}]} ight)$$

Question 3

What is the pH of a buffer solution containing 0.050 M lactic acid and 0.060 M sodium lactate? $$K_a = 1.4 	imes 10$$^{-4}$$.

Accepted Answer

$$	ext{pH} = 4.02$$

Question 4

Which statement best describes the buffer capacity?

Accepted Answer

Buffer capacity is the amount of acid or base that can be added before the pH changes drastically.

Question 5

Blood is buffered at pH = 7.40 ± 0.05. Which conjugate acid-base pair is most important in maintaining this pH?

Accepted Answer

H2CO3 / HCO3-

Question 6

What is the [HPO4$$^{2-}$$]/[H2PO4$$^-$$] ratio in blood at pH = 7.40 if $$K_a(H2PO4$^-) = 6.2$$ 	imes $$10^{-8}$?

Accepted Answer

$$1.58$$

Question 7

A buffer solution contains 0.40 M NaH2PO4 and 0.25 M Na2HPO4. What is the pH after 0.10 mol of NaOH is added to 1.00 L of this buffer? $$K_a(H2PO4$^-) = 6.2$$ 	imes $$10^{-8}$.

Accepted Answer

$$	ext{pH} = 7.28$$

Question 8

Which indicator would be most suitable for a titration with an equivalence point at pH = 7.00?

Accepted Answer

Bromothymol Blue (pKa = 7.1)

Question 9

During the titration of 50.0 mL of 0.100 M HCl with 0.100 M NaOH, what is the pH after 40.0 mL of NaOH is added?

Accepted Answer

$$	ext{pH} = 1.95$$

Question 10

What volume of 0.0875 M H2SO4 is required to neutralize 25.0 mL of 0.234 M NaOH?

Accepted Answer

$$33.4 	ext{ mL}$$

Question 11

Which equation correctly represents the solubility product constant ($$K_{sp}) $$for Ca3(PO4)2?

Accepted Answer

$$K_{sp} = [Ca$$^{2+}$$]^3[PO_4$^{3-}]^2$$

Question 12

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

Accepted Answer

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

Question 13

Which salt will precipitate first when slowly adding HCl(aq) to a solution that is 0.010 M in Cu+ and 0.500 M in Pb2+? $$K_{sp}$$ for PbCl2 and CuCl are $$1.7 	imes 10$$^{-5}$$ and 1.9$$ 	imes $$10^{-7}$$, respectively.

Accepted Answer

CuCl

Question 14

What is the effect of adding NaCl to a saturated solution of AgCl?

Accepted Answer

AgCl becomes less soluble due to the common ion effect.

Question 15

Which of the following best describes amphoterism?

Accepted Answer

A compound that can act as either an acid or a base.

Question 16

A solution is prepared by mixing 30.0 mL of 3.7 × 10$$^{-3} M Sr(NO$_3$$)$$_2$$ and 25.0 mL of 0.02 M Na$$_2SO$_4. $$Will SrSO$$_4$$ precipitate? $$K_{sp} of $$SrSO$$_4$$ = $$2.8 	imes 10$$^{-7}$$.

Accepted Answer

Q = $$1.8 	imes 10$$^{-5}$$; Yes

Question 17

If S represents the molar concentration of Mn$$^{2+}$$ ions in a saturated solution of Mn(OH)$$_2 at $$equilibrium, what is the correct relationship between molar solubility and $$K_{sp}$$?

Accepted Answer

$$K_{sp} = [S][2S]^2 = 4S^3$

Question 18

Which of the following is NOT a requirement for a buffer solution?

Accepted Answer

Contains a strong acid and a strong base.

Aqueous Equilibria: Buffers, Titrations, and Solubility

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