Question

A nitric acid solution (HNO3) has a molar concentration of 0.00044 M. Calculate the [H3O+],[OH-] and the pH of the solution. Remember that Kw=1.0*10^-14M^2

Answer 1

[H₃O⁺]=4.4 x 10⁻⁴

pH=3.357

[OH⁻] = 2.28 x 10⁻¹¹

Further explanation

Given

HNO3 concentration = 0.00044 M

Required

[H3O+],[OH-] and the pH

Solution

HNO₃ = strong acid

HNO₃ ⇒ H₃O⁺ + NO₃⁻

[H₃O⁺]=[HNO₃]=4.4 x 10⁻⁴

For strong acid pH=-log[H₃O⁺]

pH=-log 4.4 x 10⁻⁴ = 4-log 4.4 =3.357

pOH+pH=pKw

pOH+3.357=14

pOH=14-3.357=10.643

pOH=-log[OH⁻]

$\tt [OH^-]=10^{-10.643}=2.28\times 10^{-11}$