Question detail
Explain why the pH of a solution of hydrochloric acid (a strong acid) decreases more rapidly than the pH of a solution of acetic acid (a weak acid) when both are diluted with water.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Reactions of acids
Question
Explain why the pH of a solution of hydrochloric acid (a strong acid) decreases more rapidly than the pH of a solution of acetic acid (a weak acid) when both are diluted with water.
Answer
The pH of hydrochloric acid decreases more rapidly because it is a strong acid that completely ionizes in solution, resulting in a higher concentration of hydrogen ions. In contrast, acetic acid only partially ionizes, so even when diluted, the concentration of hydrogen ions remains relatively lower, leading to a slower change in pH.
Explanation
This question assesses the student's ability to compare the behavior of strong and weak acids in terms of pH changes during dilution. It encourages critical thinking about the concepts of ionization and concentration.
Common mistake
Misunderstanding pH Changes
Students often believe that diluting a strong acid will change its pH more significantly than diluting a weak acid.
Emphasize that while both strong and weak acids will have their pH increase upon dilution, the strong acid will still remain at a lower pH compared to the weak acid after dilution.
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