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A chemist prepares 0.10 M aqueous solutions of each of the following acids - VCE - SSCE Chemistry - Question 9 - 2010 - Paper 1
Question 9
A chemist prepares 0.10 M aqueous solutions of each of the following acids. Which solution has the lowest pH? A. CH₃COOH B. HNO₂ C. HCN D. HOCl
Worked Solution & Example Answer:A chemist prepares 0.10 M aqueous solutions of each of the following acids - VCE - SSCE Chemistry - Question 9 - 2010 - Paper 1
Step 1
Identify the Acid Strength
Answer
To determine which acid has the lowest pH in a 0.10 M solution, it is essential to identify the strength of each acid. Strong acids fully dissociate in solution, while weak acids only partially dissociate.
- HNO₂ (Nitrous Acid): This is a weak acid, but it has a greater dissociation compared to the others.
- CH₃COOH (Acetic Acid): A weak acid with a low dissociation constant (Ka).
- HCN (Hydrocyanic Acid): A very weak acid with a negligible dissociation constant.
- HOCl (Hypochlorous Acid): Also a weak acid, but stronger than acetic acid.
Thus, among these acids, HNO₂, being a stronger weak acid, would produce more H⁺ and thereby have a lower pH compared to the others.
Step 2