A certain mixture of HCl and `CH_3-COOH` is `0.1 M` in each of the acids.20 ml of this solution is titrated against 0.1M NaOH.By how many units does t
A certain mixture of HCl and `CH_3-COOH` is `0.1 M` in each of the acids.20 ml of this solution is titrated against 0.1M NaOH.By how many units does the pH changes form the start to the stage when the HCl is almost completely neutralised ? `K_a` for acetic acid=`1.8xx10^(-5)`.
A. 2.03
B. 0.775
C. 2.325
D. 3.175
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Correct Answer - A
Initial `[H^+]`=0.1 (`H^+` from weak acid can neglect )
After neutralisation of HCl volume would double, hence concentration of `CH_3COOH=(0.1xx20)/40=0.05`
`[H^+]=sqrt(K_aC)`
`[H^+]=sqrt(1.8xx10^(-5)xx0.05)=9.48xx10^(-4)`
pH=3.03
change in pH unit =3.03-1=2.03
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