Practice pH in Chemistry

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

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Quick Recap

A logarithmic scale (typically 0 to 14) that quantifies the hydrogen ion concentration [H+][\text{H}^+] in an aqueous solution: at 25°C, values below 7 are acidic, 7 is neutral, and above 7 is basic.

A number that tells you: acid (low), neutral (7), base (high).

Showing a random 20 of 50 problems.

Example 1

hard
100 mL100\,\text{mL} of 0.020 M0.020\,\text{M} HCl is diluted to 200 mL200\,\text{mL}. Find the new pH.

Example 2

medium
[H+]=4×10−5 M[\text{H}^+] = 4 \times 10^{-5}\,\text{M}. Find the pH (use log⁡4≈0.60\log 4 \approx 0.60).

Example 3

easy
At 25°C, water has [H+]=10−7 M[\text{H}^+] = 10^{-7}\,\text{M}. What is its pH?

Example 4

easy
What is the pOH of a solution with pH 4 at 25°C?

Example 5

easy
True or false: a one-unit change in pH means [H+][\text{H}^+] changes by a factor of 10.

Example 6

medium
Two solutions have pH 3 and pH 5. Find each [H+][\text{H}^+] and the ratio of acidities.

Example 7

challenge
0.0050 mol0.0050\,\text{mol} of HCl is dissolved to make 0.50 L0.50\,\text{L} of solution. Find [H+][\text{H}^+] and pH.

Example 8

challenge
50 mL50\,\text{mL} of 0.10 M0.10\,\text{M} HCl is mixed with 50 mL50\,\text{mL} of water. Find the resulting pH (strong acid).

Example 9

hard
Equal volumes of pH 2 and pH 4 strong-acid solutions are mixed. Find the pH of the mixture (use log⁡2≈0.30\log 2 \approx 0.30).

Example 10

challenge
Concentrated HCl can have [H+]=12 M[\text{H}^+] = 12\,\text{M}. Estimate the pH (use log⁡12≈1.08\log 12 \approx 1.08).

Example 11

challenge
Equal volumes of pH 3 and pH 5 strong-acid solutions are mixed. Estimate the pH of the mixture.

Example 12

easy
Calculate the pH of a solution with [H+]=1.0×10−4 M[\text{H}^+] = 1.0 \times 10^{-4}\,\text{M}.

Example 13

medium
A strong acid has [H+]=5×10−3 M[\text{H}^+] = 5 \times 10^{-3}\,\text{M}. Estimate the pH (use log⁡5≈0.70\log 5 \approx 0.70).

Example 14

medium
A solution of pH 8.0 is changed to pH 6.0. By what factor does [H+][\text{H}^+] change?

Example 15

easy
At 25°C, pH ++ pOH == ?

Example 16

easy
Is a pH of 6 acidic, neutral, or basic at 25°C?

Example 17

easy
A solution has [H+]=10−3 M[\text{H}^+]=10^{-3}\,\text{M}. Find the pH.

Example 18

medium
A solution changes from pH 4 to pH 7. By what factor did [H+][\text{H}^+] change?

Example 19

hard
A strong base solution has [OH−]=2×10−4 M[\text{OH}^-] = 2 \times 10^{-4}\,\text{M}. Find the pH at 25°C (use log⁡2≈0.30\log 2 \approx 0.30).

Example 20

easy
Which is more acidic: a solution of pH 1 or pH 6?
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