Find Ka from pH.
Understand the Problem
The question is asking how to find the acid dissociation constant (Ka) from a given pH value. This typically involves using the relationship between pH and the concentration of hydronium ions [H3O+] to calculate Ka for a weak acid.
Answer
Ka = ([H⁺][A⁻]) / [HA]
To find Ka given the pH, use the formula Ka = ([H⁺][A⁻]) / [HA]
Answer for screen readers
To find Ka given the pH, use the formula Ka = ([H⁺][A⁻]) / [HA]
More Information
The steps involve calculating the [H⁺] concentration from the pH, assuming that [H⁺] = [A⁻], and substituting the values back into the Ka expression.
Tips
Ensure the solution is indeed a weak acid and that the assumptions made (such as negligible change in initial concentration of HA) are valid.
Sources
- Calculating a Ka Value from a Known pH - Chemistry LibreTexts - chem.libretexts.org
- How to Calculate the Ka of a Weak Acid from pH - Study.com - study.com
- Flexi answers - How to calculate Ka from pH? | CK-12 Foundation - ck12.org
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