Question

Calculate pH of solution obtained by mixing 50ml of 0.2M HCL with 50ml of 0.1M NaOH?

Answer 1

First we need to find the number of moles used:
`n("HCl")=0.2*50/1000=0.01mol`
`n("NaOH")=0.1*50/1000=0.005mol`

`((n("HCl"),:,n("NaOH")),(1,:,2))`

`"HCl"+"NaOH"->"H"_2"O"+"NaCl"`

So, `0.005` mol of `"HCl"` remain.

`0.005/(100/1000)=0.05mol` `dm^-3` (100 comes from the total volume being 100mL)

`"pH"=-log([H^+(aq)])=-log(0.05)~~1.30`