Question

What is the ph of a 0.085 m solution of nitrous acid (hno2) that has a ka of 4.5 × 10-4?

Answer 1

Data Given:
Molarity = 0.085 M

Ka = 4.5 × 10⁻⁴
To Find:
pH = ?
Solution:
First find out the concentration of [H⁺] Ions using following formula,

[H⁺] =
`√(Ka . M)`

Puting values,

[H⁺] =
`√(0.00045 * 0.085)`

[H⁺] =
`√(0.00003825)`

[H⁺] = 0.00618465843
Or,
[H⁺] = 6.18 × 10⁻³

Calculate pH as,

pH = -log [H⁺]

pH = -log (6.18 × 10⁻³)

pH = 2.20