Q: Which of the following statements about the pH of a $$0.010\ \mathrm{M}\ \mathrm{$$HClO_4$$}$$ solution is correct?

$$\mathrm{pH} = 2.00$$, because $$[\mathrm{H}^+] = 1.0 \times 10$$^{-2}$$\ \mathrm{M}.$$

Question 1

Which of the following statements best describes the relationship between pH and pOH at 25°C?

Accepted Answer

$$\mathrm{pH} + \mathrm{pOH} = 14$$

Question 2

A solution has $$[\mathrm{H}^+] = 1.0 	imes 10$$^{-4}$$\ \mathrm{M}. $$What is the pH of this solution?

Accepted Answer

$$\mathrm{pH} = 4$$

Question 3

Which of the following acids is most likely to be found in citrus fruits and is responsible for their sour taste?

Accepted Answer

Citric acid ($$\mathrm{H_3C_6H_5O_7})$$

Question 4

Which of the following bases is commonly used as an antacid and a source of $$\mathrm{CO_2$} in $$baking?

Accepted Answer

Sodium bicarbonate ($$\mathrm{$$NaHCO_3$$})$$

Question 5

Given a $$0.0015\ \mathrm{M}$$ solution of $$\mathrm{KOH} at$$ $$25^\circ\mathrm{C}$$, which pair of mathematical expressions correctly calculates the pH and pOH?

Accepted Answer

$$\mathrm{pH} = 14.00 - ( -\log(0.0015) )$$ and $$\mathrm{pOH} = -\log(0.0015)$$

Question 6

Which of the following statements about the pH of a $$0.010\ \mathrm{M}\ \mathrm{$$HClO_4$$}$$ solution is correct?

Accepted Answer

$$\mathrm{pH} = 2.00$$, because $$[\mathrm{H}^+] = 1.0 	imes 10$$^{-2}$$\ \mathrm{M}.$$

Question 7

Which acid in the table below is most likely to be hydrochloric acid ($$\mathrm{HCl}$$)?

| Concentration (M) | pH of Acid 1 | pH of Acid 2 | pH of Acid 3 | pH of Acid 4 |
|------------------|-------------|-------------|-------------|-------------|
| 0.010            | 3.44        | 2.00        | 2.92        | 2.20        |
| 0.050            | 3.09        | 1.30        | 2.58        | 1.73        |
| 0.10             | 2.94        | 1.00        | 2.42        | 1.55        |
| 0.50             | 2.69        | 0.30        | 2.08        | 1.16        |
| 1.00             | 2.44        | 0.00        | 1.92        | 0.98        |

Accepted Answer

Acid 2

Question 8

Which of the following best explains why $$\mathrm{HCl} is a $$strong acid while $$\mathrm{CH_4$} is $$not acidic?

Accepted Answer

The H–Cl bond is more polar and weaker than the H–C bond, making it easier to donate a proton.

Question 9

A buffer solution is prepared by mixing equal volumes of $$0.20\ \mathrm{M}\ \mathrm{HC_2H_3O_2}$$ and $$0.40\ \mathrm{M}\ \mathrm{NaC_2H_3O_2}. $$What happens if a small amount of $$\mathrm{HCl} is $$added?

Accepted Answer

The pH will decrease only slightly because the $$\mathrm{H^+}$$ ions will react with $$\mathrm{C_2H_3O_2^-}$$ ions.

Question 10

Which equation represents the net ionic equation for the neutralization of a strong acid with a strong base?

Accepted Answer

$$\mathrm{H^+ (aq) + OH^- (aq) \rightarrow H_2O (l)}$$

Question 11

Which of the following pairs, when combined in equimolar amounts, results in a buffer with a pH closest to 7.5?

| Acid | $$K_a$$ |
|------|-------|
| HNO$$_2$$ | $$4.0 	imes 10$$^{-4}$$ |
| HC_3$H_5$O_2$ | 1.3$$ 	imes $$10^{-5}$$ |
| HClO | $$3.0 	imes 10$$^{-8}$$ |
| HOC_6$H_5$ | 1.6$$ 	imes $$10^{-10}$$ |

Accepted Answer

HClO and ClO$$^-$$

Question 12

A student titrates $$25.0\ \mathrm{mL} of an $$unknown monoprotic acid with $$0.100\ \mathrm{M}\ \mathrm{NaOH}. $$The titration curve shows the equivalence point at $$25.0\ \mathrm{mL} of $$NaOH added and the midpoint at pH $$= 3.8. $$What is the $$pK_a of $$the acid?

Accepted Answer

$$pK_a = 3.8$$

Question 13

Which of the following best describes the effect of increasing the concentration of both components of a buffer while keeping their ratio constant?

Accepted Answer

The buffer's capacity to neutralize added acid or base increases.

Question 14

Which of the following is true at the half-equivalence point during the titration of a weak acid with a strong base?

Accepted Answer

The pH equals the pKa of the acid.

Question 15

Which of the following best explains why the addition of a small amount of strong acid to a buffer solution does not significantly change the pH?

Accepted Answer

The strong acid is neutralized by the conjugate base in the buffer.

Question 16

Which of the following equations is the Henderson-Hasselbalch equation for a buffer containing a weak acid and its conjugate base?

Accepted Answer

$$\mathrm{pH} = \mathrm{p}K_a + \log \left( \frac{[	ext{Base}]}{[	ext{Acid}]} ight)$$

Acids, Bases, and Aqueous Equilibria: A Comprehensive Study Guide

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