Question

A buffer solution is prepared in which the concentration of nh3 is 0.30 m and the concentration of nh4 + is 0.20 m. Pkb for nh3 equal to 4.74, what is the ph of this solution ?

Answer 1

ph is 9.16 the detailed answer in the image added

Answer 2

Answer: The pH of the solution is 9.44

Explanation:

The chemical equation for the reaction of ammonia with water follows:

$NH_3+H_2O\rightarrow NH_4^++OH^-$

To calculate the pOH of basic buffer, we use the equation given by Henderson Hasselbalch:

$pOH=pK_b+\log(\frac{[salt]}{[base]})$

$pOH=pK_b+\log(\frac{[NH_4^+]}{[NH_3]})$

We are given:

$pK_b=4.74$

$[NH_4^+]=0.20M$

$[NH_3]=0.30M$

Putting values in above equation, we get:

$pOH=4.74+\log(\frac{0.20}{0.30})\\\\pOH=4.56$

To calculate pH of the solution, we use the equation:

$pH+pOH=14\\pH=14-4.56=9.44$

Hence, the pH of the solution is 9.44