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Effect of dilution on acid pH
Explain what happens to the pH of an acid as the acid is diluted with water.
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Marking points
- 1 States that pH increases on dilution.
- 2 Explains that hydrogen-ion concentration decreases.
Full-mark answer
The pH increases because dilution lowers the concentration of hydrogen ions, H⁺, in the solution.
Why this answer loses marks
The pH decreases because water is added.
Dilution reduces hydrogen-ion concentration, so the pH moves upward.