Question

A solution is prepared at that is initially in methylamine , a weak base with , and in methylammonium chloride . Calculate the pH of the solution. Round your answer to decimal places.

Answer 1

The question is incomplete, here is a complete question.

A solution is prepared at 25 °C that is initially 0.18 M in methylamine (CH₃NH₂), a weak base with
`K_b=4.4* 10^(-4)`, and 0.35 M in methylammonium bromide (CH₃NH₃Br). Calculate the pH of the solution. Round your answer to 2 decimal places.

Answer : The pH of the solution is, 10.36

Explanation :

First we have to calculate the value of
`pK_b`.

`pK_b=-\log K_b`

`pK_b=-\log (4.4* 10^(-4))`

`pK_b=3.35`

Now we have to calculate the value of pOH.

Using Henderson Hesselbach equation :

`pOH=pK_b+\log ([Salt])/([Base])`

`pOH=pK_b+\log ([CH_3NH_3Br])/([CH_3NH_2])`

Now put all the given values in this equation, we get :

`pOH=3.35+\log (0.35)/(0.18)`

`pOH=3.64`

Now we have to calculate the pH.

`pH+pOH=14\\\\pH=14-pOH\\\\pH=14-3.64=10.36`

Therefore, the pH of the solution is, 10.36