Question

What is the approximate pH of a 0.005 M solution of H2SO4?
A) 1
B) 2
C) 5
D) 9
E) 13

Answer 1

Answer on Question#45029 – Chemistry – Inorganic Chemistry

Question:

What is the approximate pH of a 0.005 M solution of H₂SO₄?

A) 1

B) 2

C) 5

D) 9

E) 13

Answer:

Sulfuric acid is ionized in water solution according to the following equations:

$$\mathrm{H_2SO_4} \rightarrow \mathrm{HSO_4^{2-}} + \mathrm{H^+}$$ $$\mathrm{HSO_4^{2-}} \leftrightarrow \mathrm{SO_4^{2-}} + \mathrm{H^+}$$

The second reaction is reversible and for approximate calculations can be neglected. The concentration of $\mathrm{H^+}$ is the same as $\mathrm{H_2SO_4} \, 0.005\,\mathrm{M}$.

$$\mathrm{pH} = -\log(\mathrm{H^+}) = -\log(0.005) = 2.3 \approx 2$$

Option B) is correct.

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