# What is the PH of a 1M CH3COONa? Ka of acetic acid=1.8x10-5,Kw=10-14 mol2/l2 Option 1) 2.4 Option 2) 3.6 Option 3) 4.8 Option 4) 9.4

As learnt in

Ionization constant of weak acids -

Consider

$HX(aq)+H_{2}O(l)\rightleftharpoons H_{3}O^{+}(aq)+\bar{X}(aq)$

$K_{a}=dissociation\:or\:ionization\:constant$

- wherein

$K_{a}=\frac{C^{2}\:\alpha ^{2}}{C(1-\alpha )}$

$K_{a}=\frac{C\alpha ^{2}}{1-\alpha }$

$C=initial\:concentration\:of\:undissociated\:acid$

$\alpha =extent\:upto\:which\:HX\:is\:ionized\:into\:ions.$

$PH = 7-\frac{1}{2} p \:\: K_{a} - \frac{1}{2} log C$

$\Rightarrow PH = 7+\frac{1}{2} log (1.8\times 10^{-5}) - \frac{1}{2} log (1)$

$=9.37$ or $9.4$

Option 1)

2.4

This solution is incorrect

Option 2)

3.6

This solution is incorrect

Option 3)

4.8

This solution is incorrect

Option 4)

9.4

This solution is correct

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