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I’m still working on my concepts related to chemical equilibrium. I came across this question:
10mL of a weak acid HA is $20 \%$ dissociated in water. This solution is completely neutralised by $10 \mathrm{~mL}$ of $10^{-3} \mathrm{M}$ of $\mathrm{NaOH}$.
Is $[\mathrm{HA}]=10^{-3} \mathrm{M}$ or is $\left[\mathrm{H}^{+}\right]=10^{-3} ?$
Why is it wrong to say that since $\mathrm{NaOH}$ completely dissociates, and solution is neutral, $\left[\mathrm{OH}^{-}\right]=$ $10^{-3} \mathrm{M}=\left[\mathrm{H}^{+}\right] ?$
Here, [.] denotes concentration.