Question

How many moles of HCl needs to be added to a solution containing 0.10 mol of NH3 to make a buffer of pH 9.26

Answer 1

The correct solution is "0.05 mol".

Step-by-step explanation:

According to the question,

⇒
`NH_(3)(aq)+HCL(aq)\rightarrow NH_(4)^+Cl^-(aq)`

0.10 x 0

(0.10-x) 0 x

Now,

`pH=pKa+log([NH_(4)Cl])/([NH_(3)])`

`9.26=9.26+log((x)/(0.10-x) )`

`log((x)/(0.10-x))=0`

`(x)/(0.10-x)=1`

`2x=0.10`

`x=0.05` (moles of HCL needed)