Q: Given a 0.10 M solution of HCl (a strong acid), what is the pH of the solution at 25 °C?

$$\text{pH} = -\log(0.10) = 1$$

Q: A buffer solution is prepared using acetic acid ($$\text{CH}_3\text{COOH}) $$and sodium acetate ($$\text{CH}_3\text{COONa}). $$Which equation would you use to calculate the pH of this buffer?

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

Q: A solution has $$[\text{H}_3\text{O}^+] = 2.5 \times 10$$^{-5}$$ M. What is the pH?

$$\text{pH} = -\log(2.5 \times 10$$^{-5}$$) = 4.60$$

Q: If the $$K_a of a $$weak acid is $$1.8 \times 10$$^{-5}$$, what is its pK_a$?

$$pK_a = -\log(1.8 \times 10$$^{-5}$$) = 4.74$$

Q: What is the pH of a solution with $$[OH^-] = 1.0 \times 10$$^{-3}$$ M at 25 °C?

$$\text{pOH} = 3; \text{pH} = 11$$

Question 1

Which of the following statements best describes the relationship between acid strength and its conjugate base?

Accepted Answer

A strong acid has a very weak conjugate base.

Question 2

Given a 0.10 M solution of HCl (a strong acid), what is the pH of the solution at 25 °C?

Accepted Answer

$$	ext{pH} = -\log(0.10) = 1$$

Question 3

Which of the following acids is the strongest based on periodic trends?

Accepted Answer

HI

Question 4

A buffer solution is prepared using acetic acid ($$	ext{CH}_3	ext{COOH}) $$and sodium acetate ($$	ext{CH}_3	ext{COONa}). $$Which equation would you use to calculate the pH of this buffer?

Accepted Answer

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

Question 5

Which salt will produce a basic solution when dissolved in water?

Accepted Answer

NaF

Question 6

Calculate the pOH of a 0.020 M solution of Sr(OH)$$_2 at 25$$ °C.

Accepted Answer

$$	ext{pOH} = -\log(0.040)$$

Question 7

Which of the following best explains why HClO$$_4 is a $$stronger acid than HClO$$_3$$?

Accepted Answer

HClO$$_4$$ has more oxygen atoms, which stabilize the conjugate base.

Question 8

A solution has $$[	ext{H}_3	ext{O}^+] = 2.5 	imes 10$$^{-5}$$ M. What is the pH?

Accepted Answer

$$	ext{pH} = -\log(2.5 	imes 10$$^{-5}$$) = 4.60$$

Question 9

Which of the following combinations will result in a buffer solution?

Accepted Answer

NH$$_3$$ and NH$$_4Cl$$

Question 10

If the $$K_a of a $$weak acid is $$1.8 	imes 10$$^{-5}$$, what is its pK_a$?

Accepted Answer

$$pK_a = -\log(1.8 	imes 10$$^{-5}$$) = 4.74$$

Question 11

A 0.10 M solution of a weak acid (HA) has a pH of 3.0. What is the percent ionization of the acid?

Accepted Answer

1.0%

Question 12

Which of the following best describes the common ion effect?

Accepted Answer

The addition of an ion already present in equilibrium suppresses the ionization of a weak acid or base.

Question 13

Which of the following statements is true about the titration of a weak acid with a strong base?

Accepted Answer

The equivalence point occurs at pH \u003e 7.

Question 14

What is the pH of a solution with $$[OH^-] = 1.0 	imes 10$$^{-3}$$ M at 25 °C?

Accepted Answer

$$	ext{pOH} = 3; 	ext{pH} = 11$$

Question 15

Which of the following is a polyprotic acid?

Accepted Answer

H$$_2SO$_4$$

Question 16

A buffer is most effective when:

Accepted Answer

The pH is close to the pKa of the weak acid.

Question 17

If $$K_w = 1.0 	imes 10$$^{-14}$$ at 25 °C, what is the relationship between K_a$ and K_b$ for a conjugate acid-base pair?

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 18

Which of the following salts will produce an acidic solution when dissolved in water?

Accepted Answer

NH$$_4Cl$$

Question 19

A student titrates 25.0 mL of 0.100 M NH$$_3$$ with 0.100 M HCl. At the equivalence point, the pH is 5.28. What does this indicate about the solution?

Accepted Answer

The solution is acidic due to the formation of NH$$_4^+.$$

Question 20

Which of the following best describes the pH at the equivalence point for the titration of a strong base with a strong acid?

Accepted Answer

pH = 7

Acids, Bases, and Aqueous Ionic Equilibria: Study Notes for General Chemistry

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