Question

pH of a solution which contains 0.15 M NH4OH and 0.3
M NH4CI is (pkb for NH4OH is 4.7)
a) 5
b) 8
c) 9
d) 12.​

Answer 1

Answer:

d) 12. answer ho jaye Bhai

Answer 2

pH of a solution is 9 and option (c) is correct.

Explanation:

Given:

A solution which contains 0.15 M $NH_{4} OH$ and 0.3 M $NH_{4} Cl$.

pkb for $NH_{4} OH$is 4.7.

To Find:

pH of a solution.

Formula Used:

$pOH$ of basic buffer solution is  give by Henderson Hasselbalch equation.

$pOH=pK_{b} +log_{10} \frac{salt }{base }$    ------------------ formula no.01.

Solution:

As given-a solution which contains 0.15 M $NH_{4} OH$ and 0.3 M $NH_{4} Cl$.

Molarity of $NH_{4} OH$( base) = 0.15 M

Molarity of $NH_{4} Cl$ ( salt) =0.3 M

As given- pkb for $NH_{4} OH$  is 4.7.

pkb for $NH_{4} OH$ = 4.7.

Applying the formula no.01.

$pOH=pK_{b} +log_{10} \frac{salt }{base }$

$pOH=pK_{b} +log_{10} \frac{NH_{4}Cl }{NH_{4}OH }$

        $=4.7+log_{10} \frac{0.30 }{0.15 }$

       $=4.7+log_{10} 2$

       $=4.7+0.3010\\=5.001$

$pH=14-pOH$

      $=14-5.001$

      $=8.999 \ or\ approx.\ 9.$

Thus,pH of a solution is 9 and option (c) is correct.

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