alleryStart learning →What are the hydronium and hydroxide concentrations in pure water at 25 degrees Celsius?
ABoth equal 1.0 x 10^-14 M in pure water
BHydronium is 1.0 x 10^-7 M, hydroxide zero
CBoth equal 1.0 x 10^-7 M in the pure liquid
DHydroxide is 1.0 x 10^-7 M, hydronium zero
Answer & Solution
Correct answer: C. Both equal 1.0 x 10^-7 M in the pure liquid
1. Autoionisation makes one hydronium ion for every hydroxide ion, so the two are equal.
2. Their product is fixed at 1.0 x 10^-14, so each concentration squared equals that value.
3. Taking the square root of 1.0 x 10^-14 gives 1.0 x 10^-7 mol per litre.
4. Neither ion is ever absent, since the autoionisation equilibrium is always established.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 14 "Acid-Base Equilibria", section 14.1 Brønsted-Lowry Acids and Bases_
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