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What would be the pH of a 0.1 mol L<sup>−1</sup> solution of sulfuric acid? (A) Less than 1.0 (B) Exactly 1.0 (C) Between 1.0 and 7.0 (D) Greater than 7.0 - HSC - SSCE Chemistry - Question 8 - 2005 - Paper 1
Question 8
What would be the pH of a 0.1 mol L<sup>−1</sup> solution of sulfuric acid? (A) Less than 1.0 (B) Exactly 1.0 (C) Between 1.0 and 7.0 (D) Greater than 7.0
Worked Solution & Example Answer:What would be the pH of a 0.1 mol L<sup>−1</sup> solution of sulfuric acid? (A) Less than 1.0 (B) Exactly 1.0 (C) Between 1.0 and 7.0 (D) Greater than 7.0 - HSC - SSCE Chemistry - Question 8 - 2005 - Paper 1
Step 1
Determine the dissociation of sulfuric acid
Answer
Sulfuric acid (H<sub>2</sub>SO<sub>4</sub>) is a strong acid that dissociates completely in solution. The first dissociation is:
ightarrow H^+ + HSO_4^-$$ This means that for every mole of sulfuric acid, we get one mole of hydrogen ions (H<sup>+</sup>) from the first dissociation.Step 2
Calculate the hydrogen ion concentration
Answer
Given that the concentration of sulfuric acid is 0.1 mol L<sup>−1</sup>, this means that the concentration of hydrogen ions from the first dissociation is also 0.1 mol L<sup>−1</sup>. The HSO<sub>4</sub><sup>-</sup> can also dissociate to produce more H<sup>+</sup> ions:
ightleftharpoons H^+ + SO_4^{2-}$$ For a dilute solution (like 0.1 mol L<sup>−1</sup>), we usually assume that this contributes a minor amount of additional H<sup>+</sup>, but this can be considered in calculations if needed. However, for practical purposes, let’s consider the H<sup>+</sup> concentration to still be about 0.1 mol L<sup>−1</sup>.Step 3
Step 4