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1. The Chemical World9m
- The Scientific Method
  9m
2. Measurement and Problem Solving2h 19m
3. Matter and Energy2h 15m
4. Atoms and Elements2h 33m
5. Molecules and Compounds1h 50m
6. Chemical Composition1h 23m
7. Chemical Reactions1h 43m
8. Quantities in Chemical Reactions1h 8m
9. Electrons in Atoms and the Periodic Table2h 32m
10. Chemical Bonding2h 10m
11 Gases2h 7m
12. Liquids, Solids, and Intermolecular Forces1h 11m
13. Solutions3h 1m
14. Acids and Bases2h 14m
15. Chemical Equilibrium1h 27m
16. Oxidation and Reduction1h 33m
17. Radioactivity and Nuclear Chemistry53m

14. Acids and Bases

The pH Scale

Introduction to Chemistry

14. Acids and Bases

The pH Scale

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Multiple Choice

What is the Kw of pure water at 20.0°C, if the pH is 7.083?

8.26 × 10^-8

6.82 × 10^-15

7.23 × 10^-14

1.00 × 10^-14

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Verified step by step guidance

Understand that Kw is the ion product constant for water, which is the product of the concentrations of hydrogen ions [H⁺] and hydroxide ions [OH⁻] in water.

Recall that pH is defined as the negative logarithm (base 10) of the hydrogen ion concentration: \( \text{pH} = -\log[\text{H}^+] \).

Use the given pH value to find the concentration of hydrogen ions: \( [\text{H}^+] = 10^{-\text{pH}} \). Substitute the given pH of 7.083 into this formula.

Since pure water is neutral, the concentration of hydroxide ions [OH⁻] is equal to the concentration of hydrogen ions [H⁺]. Therefore, \( [\text{OH}^-] = [\text{H}^+] \).

Calculate Kw by multiplying the concentrations of hydrogen ions and hydroxide ions: \( K_w = [\text{H}^+][\text{OH}^-] \). Use the concentration found in step 3 for both [H⁺] and [OH⁻].