Q: A solution at 25°C has a hydronium ion concentration of $$1.0 \times 10$$^{-3}$$ M. What is its pH?

$$pH = -\log(1.0 \times 10$$^{-3}$$) = 3.0$$

Q: A 0.010 M solution of NaOH is prepared. What is the pH of this solution at 25°C?

$$[OH^-] = 0.010 M$, [H_3O^+] = \frac{1.0 \times 10$$^{-14}$$}{0.010} = 1.0 \times 10$$^{-12}$$ M$$, pH = -\log(1.0 \times $$10^{-12}) = 12.0$

Q: A solution has $$[H_3O^+] = 2.0 \times 10$$^{-4}$$ M. What is the $$[OH^-]$$ at 25°C?

$$[OH^-] = \frac{1.0 \times 10$$^{-14}$$}{2.0 \times 10$$^{-4}$$} = 5.0 \times 10$$^{-11}$$ M

Q: Which of the following statements is true for a neutral solution at 25°C?

$$[H_3O^+] = [OH^-] = 1.0 \times 10$$^{-7}$$ M$

Q: Which acid from the table has the highest acid strength based on its $$K_a$$ value?

Hydronium ion ($$K_a = 5.5 \times 10^0$)

Q: A student titrates 10.0 mL of HCl with 20.0 mL of 5.0 \times $$10^{-3} M $$NaOH. What is the molarity of the HCl solution?

$$M_{HCl} = \frac{1.0 \times 10$$^{-4}$$ \text{ mol}}{10.0 \text{ mL}} \times \frac{1000 \text{ mL}}{1 \text{ L}} = 1.0 \times 10$$^{-2}$$ M

Question 1

Which of the following statements best explains why the ionization constant of water ($$K_w) $$increases as temperature increases?

Accepted Answer

The dissociation of water is an endothermic process, so increasing temperature shifts equilibrium toward products.

Question 2

A solution at 25°C has a hydronium ion concentration of $$1.0 	imes 10$$^{-3}$$ M. What is its pH?

Accepted Answer

$$pH = -\log(1.0 	imes 10$$^{-3}$$) = 3.0$$

Question 3

If the pH of a solution is 5.0, what is the hydronium ion concentration?

Accepted Answer

$$[H_3O^+] = 10$$^{-5}$$ M

Question 4

A 0.010 M solution of NaOH is prepared. What is the pH of this solution at 25°C?

Accepted Answer

$$[OH^-] = 0.010 M$, [H_3O^+] = \frac{1.0 	imes 10$$^{-14}$$}{0.010} = 1.0 	imes 10$$^{-12}$$ M$$, pH = -\log(1.0 	imes $$10^{-12}) = 12.0$

Question 5

Which indicator would be most appropriate for determining the equivalence point in a titration between a strong acid and a strong base?

Accepted Answer

Bromothymol blue (transition range: 6.2–7.6)

Question 6

A titration curve for a weak acid and a strong base shows the equivalence point at pH \u003e 7. Which indicator would be best for this titration?

Accepted Answer

Phenolphthalein

Question 7

Which of the following materials is most likely to have a pH closest to 7.0?

Accepted Answer

Pure water

Question 8

A solution has $$[H_3O^+] = 2.0 	imes 10$$^{-4}$$ M. What is the $$[OH^-]$$ at 25°C?

Accepted Answer

$$[OH^-] = \frac{1.0 	imes 10$$^{-14}$$}{2.0 	imes 10$$^{-4}$$} = 5.0 	imes 10$$^{-11}$$ M

Question 9

Which of the following statements is true for a neutral solution at 25°C?

Accepted Answer

$$[H_3O^+] = [OH^-] = 1.0 	imes 10$$^{-7}$$ M$

Question 10

Which acid from the table has the highest acid strength based on its $$K_a$$ value?

Accepted Answer

Hydronium ion ($$K_a = 5.5 	imes 10^0$)

Question 11

A student titrates 10.0 mL of HCl with 20.0 mL of 5.0 	imes $$10^{-3} M $$NaOH. What is the molarity of the HCl solution?

Accepted Answer

$$M_{HCl} = \frac{1.0 	imes 10$$^{-4}$$ 	ext{ mol}}{10.0 	ext{ mL}} 	imes \frac{1000 	ext{ mL}}{1 	ext{ L}} = 1.0 	imes 10$$^{-2}$$ M

Question 12

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

Accepted Answer

$$pH + pOH = 14$$

Question 13

If a solution has a pH of 2.0, which of the following materials is it most similar to?

Accepted Answer

Soft drinks

Question 14

Which of the following is true for a strong acid in water?

Accepted Answer

It is completely ionized, so $$[H_3O^+]$$ equals the initial acid concentration.

Question 15

Which of the following solutions would have the highest pH?

Accepted Answer

0.100 mol NaOH in 1.00 L of H$$_2O$$

Question 16

Which of the following statements about acid-base indicators is correct?

Accepted Answer

Indicators are weak acids or bases that change color depending on pH.

Question 17

A solution has $$[OH^-] = 2.5 	imes 10$$^{-2}$$ M at 25°C. What is its $$[H_3O^+]$$?

Accepted Answer

$$[H_3O^+] = \frac{1.0 	imes 10$$^{-14}$$}{2.5 	imes 10$$^{-2}$$} = 4.0 	imes 10$$^{-13}$$ M

Question 18

Which of the following is a correct step in calculating the molarity of an unknown solution by titration?

Accepted Answer

Determine the moles of solute of the unknown solution used during the titration.

Acid-Base Titration and pH: Concepts, Calculations, and Applications

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