Question

A solution containing a mixture of lactic acid and lactate was found to have a pH of 4.26. Calculate the ratio of the lactate concentration to the lac

Answer 1

Given :

pH of solution of mixture of lactic acid and lactate is 4.26 .

To Find : $log( \dfrac{[ \text{Conc. of lactate}]}{[\text{Conc . of lactic acid }]}) = 0.4$

The ratio of the lactate concentration to the lactate .

Solution :

We know , pKa of lactic acid is :

pKa = 3.86 .

Now , the solution of lactic acid and lactate is a buffer solution .

So , pHof buffer acid is given by :

$pH=pKa+log(\dfrac{[Salt]}{[Acid]})$

Putting all given values :

$log( \dfrac{[ \text{Conc. of lactate}]}{[\text{Conc . of lactic acid }]}) = 0.4$

Taking anti log both the sides , we get :

$\dfrac{[ \text{Conc. of lactate}]}{[\text{Conc . of lactic acid }]} = 2.51$

Therefore , the ratio of the lactate concentration to the lactate is 2.51 .

Hence , this is the required solution .