The pH of solution is () — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

$\text{HNO}_3$ is a strong monoprotic acid, so it dissociates completely. $[\text{H}^+] = 4.0 \times 10^{-4}\text{ M}$. The pH is given by $-\log(4.0 \times 10^{-4}) = 4 - \log 4 = 4 - 2\log 2$. Given $\log 2 = 0.3$, we get $\text{pH} = 4 - 2(0.3) = 4 - 0.6 = 3.4$.