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Equal volumes of four 0.1 mol L⁻¹ acids were titrated with the same sodium hydroxide solution - HSC - SSCE Chemistry - Question 7 - 2010 - Paper 1
Question 7
Equal volumes of four 0.1 mol L⁻¹ acids were titrated with the same sodium hydroxide solution. Which requires the greatest volume of base to change the colour of th... show full transcript
Worked Solution & Example Answer:Equal volumes of four 0.1 mol L⁻¹ acids were titrated with the same sodium hydroxide solution - HSC - SSCE Chemistry - Question 7 - 2010 - Paper 1
Step 1
Which requires the greatest volume of base to change the colour of the indicator?
Answer
To determine which acid requires the greatest volume of sodium hydroxide (NaOH) to change the color of the indicator, we must consider the strength of each acid.
- Citric Acid: A weak triprotic acid, it can donate three protons (H⁺) in a reaction.
- Acetic Acid: A weak monoprotic acid, it can donate one proton.
- Sulfuric Acid: A strong diprotic acid, it can donate two protons (though only the first dissociation is strong).
- Hydrochloric Acid: A strong monoprotic acid, it also donates one proton completely.
Since citric acid is a triprotic weak acid, it will require more NaOH to neutralize compared to the others. Therefore, it will consume the greatest volume of NaOH to achieve a color change in the indicator. Thus, the answer is:
- (A) Citric acid