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IB DP Chemistry Questions

8.3 The pH Scale

Question 1

Which of the following formulas correctly represents the relationship between pH and the concentration of hydrogen ions?

A. pH = Log[H+]

B. pH = -Log[H+]

C. pH = [H+]

D. pH = 1/Log[H+]

Question 2

If the pH of a solution is 5, how would you classify this solution?

A. Strongly acidic

B. Weakly acidic

C. Neutral

D. Basic

Question 3

Which of the following is true about the relationship between pH and pOH?

A. pH + pOH = 14

B. pH - pOH = 7

C. pH * pOH = 14

D. pH / pOH = 2

Question 4

What does a high pKa value for an acid indicate?

A. The acid is strong.

B. The acid is weak.

C. The acid is neutral.

D. The acid is basic.

Question 5

Which of the following solutions has the lowest concentration of H+ ions?

A. pH 2

B. pH 5

C. pH 7

D. pH 9

Question 6

a) Define the term pH and explain its significance in determining the acidity or basicity of a solution. [2]

b) A solution has a [H+] concentration of 1 x 10^-5 mol/L. Use the given formula to calculate its pH. [2]

Question 7

a) Differentiate between strong and weak acids in terms of their pH values. [2]

b) If a strong acid has a pH of 2, what would be the [H+] concentration of the solution? [2]

Question 8

a) Describe the relationship between pH and pOH in a solution. [2]

b) If a solution has a pOH of 8, determine its pH. [2]

Question 9

a) Explain the significance of pKa in acid-base equilibria. [3]

b) A weak acid, HA, has a pKa of 4.5. If the pH of a solution containing this acid is 4.5, what can you infer about the concentrations of HA and A-? [2]

c) How would the pH of the solution change if more of the weak acid, HA, was added? [2]

Question 10

a) Describe the difference between the degree of ionisation in strong and weak acids. [3]

b) Why do strong acids have a higher degree of ionisation than weak acids? [2]

c) If a strong acid is diluted, how does its degree of ionisation change? [2]

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