Q: What is the pH of a solution with a hydrogen ion concentration of $$5 \times 10$$^{-3}$$ M?

$$pH = -\log(5 \times 10$$^{-3}$$) = 2.30$$

Q: If the $$K_w ($$ion product of water) at 25°C is $$1.0 \times 10$$^{-14}$$, what is the concentration of H$$^+$$ ions in pure water?

$$[H^+] = 1.0 \times 10$$^{-7}$$ M

Question 1

Which of the following best describes a Brønsted-Lowry acid?

Accepted Answer

A substance that donates a proton ($$H^+).$$

Question 2

What is the pH of a solution with a hydrogen ion concentration of $$5 	imes 10$$^{-3}$$ M?

Accepted Answer

$$pH = -\log(5 	imes 10$$^{-3}$$) = 2.30$$

Question 3

Which of the following statements about water is correct?

Accepted Answer

Water is amphoteric, meaning it can act as either an acid or a base.

Question 4

According to the Arrhenius definition, which of the following is a base?

Accepted Answer

A substance that produces $$OH^-$$ ions in water.

Question 5

A buffer solution is prepared using 0.10 M acetic acid ($$CH_3COOH) $$and 0.15 M sodium acetate ($$CH_3COONa). If $$the $$pK_a of $$acetic acid is 4.76, what is the pH of the buffer?

Accepted Answer

$$pH = 4.76 + \log(0.15/0.10) = 4.94$$

Question 6

Which equation correctly represents the acid dissociation constant ($$K_a) $$for a weak acid $$HA$$?

Accepted Answer

$$K_a = \frac{[A^-][H^+]}{[HA]}$$

Question 7

A patient’s blood pH drops from 7.4 to 7.0. What is the most likely physiological consequence?

Accepted Answer

The patient will experience acidosis.

Question 8

Which of the following best explains why buffers are important in biological systems?

Accepted Answer

Buffers maintain a constant pH, allowing enzymes and biochemical processes to function properly.

Question 9

If the $$K_w ($$ion product of water) at 25°C is $$1.0 	imes 10$$^{-14}$$, what is the concentration of H$$^+$$ ions in pure water?

Accepted Answer

$$[H^+] = 1.0 	imes 10$$^{-7}$$ M

Question 10

Which of the following is true about strong acids?

Accepted Answer

They almost completely ionize in water to donate all their protons.

Question 11

A buffer solution contains 0.11 M acetic acid and 0.14 M acetate after addition of 0.01 M HCl. If the $$pK_a of $$acetic acid is 4.76, what is the new pH?

Accepted Answer

$$pH = 4.76 + \log(0.14/0.11) = 4.86$$

Question 12

Which of the following is the correct Henderson-Hasselbalch equation for calculating the pH of a buffer?

Accepted Answer

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

Question 13

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

Accepted Answer

Weak acid and its conjugate base

Question 14

What is the $$pK_a of an $$acid with $$K_a = 1.0 	imes 10$$^{-5}$$?

Accepted Answer

$$pK_a = -\log_{10}(1.0 	imes 10$$^{-5}$$) = 5$$

Question 15

A solution has a pH of 10. What is the concentration of $$OH^-$$ ions?

Accepted Answer

$$[OH^-] = 10$$^{-4}$$ M

Question 16

Which of the following best describes the effect of adding a strong acid to a buffer solution?

Accepted Answer

The buffer neutralizes the added acid, causing only a small change in pH.

Question 17

Which of the following is a real-world example of a biological buffer system?

Accepted Answer

Carbonic acid-bicarbonate system in blood

Question 18

If a solution has a pH of 6, what is the hydrogen ion concentration?

Accepted Answer

$$[H^+] = 10$$^{-6}$$ M

Question 19

Which of the following statements about $$pK_a is $$correct?

Accepted Answer

A smaller $$pK_a$$ value indicates a stronger acid.

Acids, Bases, and Buffers: Foundations and Applications in Chemistry

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