Q&A - Ask Doubts and Get Answers
Q

Help me please, Whatis the PH of a 1MCH3COONa? Ka of acetic acid=1.8x10-5,Kw=10-14mol2/l2

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

 
Answers (1)
104 Views

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

Exams
Articles
Questions