Buffer solution question (1 Viewer)

[dchelliah]

Can someone please help with this question, and show me how to do it?

Solution C is made by mixing 57.9 mL of 0.16 M ammonium chloride (NH4Cl) with 60.4 mL of 0.26 M ammonia solution. pKa (NH4+) = 9.24
(a) Calculate the pH of Solution C.
(b)Calculate the pH of the buffer Solution C if 0.13 g of NaOH (molar mass = 40.0 g/mol) is added (assuming no change in volume).

 

[packpig123]

First you find the concentration of nh4cl and nh3 which is done by converting the amount into litres x by M/the sum of the amounts in litres
so its 0.0579x0.16/0.0579+0.0604. You do this with nh3 as well then the pH is 9.24+log(nh3/nh4)

second part find the moles which is mass/molar mass then divide the moles by the sum of the amount in litres
Youll get a value
the concentration for nh4 minus this value=x
the concentration for nh3 plus this value=y

then the ph is 9.24 + log(y/x)

 

[dchelliah]

so would the answer be 9.82?

 

[dchelliah]

Thanks so much got it right ))))))

 

[drchemJL1117]

Hi, I still confused about part (b) , could u plz show me the full answer? That will be helpful.
Cheers.