Q: Which of the following is a correct application of the Henderson-Hasselbalch equation for a buffer made from a weak acid and its conjugate base?

$$pH = pK_a + \log \left( \frac{[\text{base}]}{[\text{acid}]} \right)$$

Question 1

A solution is prepared by mixing 0.30 mol of acetic acid ($$CH_3COOH) $$and 0.30 mol of sodium acetate ($$CH_3COONa) in $$enough water to make 1.0 L of solution. What is the pH of this solution? ($$K_a$$ for acetic acid = $$1.8 	imes 10$$^{-5}$$)

Accepted Answer

$$pH = 4.74$$

Question 2

Which of the following statements is TRUE regarding the effect of adding a soluble salt containing a common ion to a solution of a weak acid at equilibrium?

Accepted Answer

The pH of the solution increases.

Question 3

A solution contains 0.20 M HF and 0.10 M HCl. What is the concentration of $$F^-$$ ions in the solution? ($$K_a$$ for HF = $$6.8 	imes 10$$^{-4}$$)

Accepted Answer

$$1.4 	imes 10$$^{-3}$$ M

Question 4

Which of the following best explains why the addition of sodium acetate to acetic acid solution decreases the $$[H^+]$$ concentration?

Accepted Answer

The common ion effect shifts the equilibrium to the left, reducing $$[H^+].$$

Question 5

A buffer solution is made by mixing 0.12 M lactic acid ($$HC_3H_5O_3) $$and 0.10 M sodium lactate ($$NaC_3H_5O_3). $$What is the pH of the buffer? ($$K_a$$ for lactic acid = $$1.4 	imes 10$$^{-4}$$)

Accepted Answer

$$pH = 3.77$$

Question 6

Which of the following is a correct application of the Henderson-Hasselbalch equation for a buffer made from a weak acid and its conjugate base?

Accepted Answer

$$pH = pK_a + \log \left( \frac{[	ext{base}]}{[	ext{acid}]} ight)$$

Question 7

A buffer is prepared by adding 0.300 mol $$CH_3COOH$$ and 0.300 mol $$CH_3COONa to $$enough water to make 1.0 L. If 0.020 mol of NaOH is added to this buffer, what will be the new pH? ($$K_a$$ for acetic acid = $$1.8 	imes 10$$^{-5}$$)

Accepted Answer

$$pH = 4.81$$

Question 8

During a strong acid-strong base titration, 50.0 mL of 0.100 M HCl is titrated with 0.100 M NaOH. What is the pH at the equivalence point?

Accepted Answer

$$pH = 7.00$$

Question 9

In the titration of 50.0 mL of 0.100 M acetic acid ($$CH_3COOH) $$with 0.100 M NaOH, what is the pH at the equivalence point? ($$K_a$$ for acetic acid = $$1.8 	imes 10$$^{-5}$$)

Accepted Answer

$$pH = 8.72$$

Question 10

Which of the following salts will have its solubility increased in acidic solution?

Accepted Answer

BaF$$_2$$

Question 11

The solubility product constant ($$K_{sp}) $$for $$CaF_2 is$$ $$3.9 	imes 10$$^{-11}$$ at 25°C. What is the molar solubility of $$CaF_2$$ in pure water?

Accepted Answer

$$2.1 	imes 10$$^{-4}$$ M$

Question 12

Which of the following actions will increase the solubility of $$AgBr in $$water?

Accepted Answer

Decreasing the pH

Question 13

A solution contains $$1.0 	imes 10$$^{-4}$$ M Ag$$^+$$ and 2.0$$ 	imes $$10^{-4} M$$ $$Pb^{2+}. $$When $$Cl^- is $$added, which salt will precipitate first? ($$K_{sp}$$ for $$AgCl = 1.8 	imes 10$$^{-10}$$, K$$_{sp}$$ for $$PbCl_2$$ = 1.7 	imes 10$$^{-5}$$)

Accepted Answer

$$AgCl$$

Question 14

Which condition must be met for an ionic compound to precipitate from a solution of its constituent ions?

Accepted Answer

$$Q \u003e K_{sp}$$

Question 15

A buffer is made by adding $$NH_4Cl to$$ $$NH_3$$ solution. If the desired pH is 9.00 and the volume is 2.0 L, how many moles of $$NH_4Cl$$ are needed? ($$K_b$$ for $$NH_3 = 1.8$$ 	imes $$10^{-5})$$

Accepted Answer

0.36 mol

Question 16

Which of the following will NOT affect the value of $$K_{sp}$$ for $$MA_3 in $$water at 298 K?

Accepted Answer

Changing the temperature of the solution

Question 17

A solution contains $$0.010 M$$ $$Ag^+$$ and $$0.30 M$$ $$NH_3. $$What is the effect of adding $$NH_3 on $$the concentration of free $$Ag^+$$ ions?

Accepted Answer

It drastically reduces the concentration of $$Ag^+$$ ions due to complex ion formation.

Question 18

Which of the following best describes the effect of a common ion on the solubility of a sparingly soluble salt?

Accepted Answer

The solubility decreases due to the common ion.

Common Ion Effect, Buffers, and pH Calculations

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드