If the pKa of lactic acid is 5,then the pH of | vedclass

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(C) Calcium lactate is the salt of a weak acid (lactic acid) and a strong base $(Ca(OH)_2)$.Formula for $pH$ of a salt of weak acid and strong base is

Vedclass · Accepted Answer

$83$

Vedclass · Answer

(C) Calcium lactate is the salt of a weak acid (lactic acid) and a strong base $(Ca(OH)_2)$.Formula for $pH$ of a salt of weak acid and strong base is:$pH = 7 + \frac{1}{2}(pKa + \log C)$Here,$C$ is the concentration of the salt,which is $0.005 \ M$.$pH = 7 + \frac{1}{2}(5 + \log(0.005))$$pH = 7 + \frac{1}{2}(5 + \log(5 	imes 10^{-3}))$$pH = 7 + \frac{1}{2}(5 + \log 5 - 3)$$pH = 7 + \frac{1}{2}(2 + 0.699) = 7 + 1.3495 = 8.3495$Rounding to the nearest integer for the form $x 	imes 10^{-1}$,we get $83.495 \approx 83 	imes 10^{-1}$.

If the $pKa$ of lactic acid is $5$,then the $pH$ of $0.005 \ M$ calcium lactate solution at $25^{\circ} \ C$ is $........ \times 10^{-1}$ (Nearest integer). The structure of lactic acid is given below:

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