chemistry help for a level ocr

grace10101

11

why do you work out the moles instead of using the initial concentrations. I can't remember why

Reply 1

grace10101

OP

11

(c). The chemist prepares 1dm3 of a buffer solution by mixing 200 cm3 of 0.200 mol dm−3 HNO2 with 800 cm3 of 0.0625 mol dm−3
sodium nitrite, NaNO2.
i. Calculate the pH of the buffer solution.
Give your answer to two decimal places.

ka = 4.69 × 10−4
and the answer is 3.43 ✔

(edited 10 months ago)

Reply 2

shapely-lobster

1

Original post by grace10101

(c). The chemist prepares 1dm3 of a buffer solution by mixing 200 cm3 of 0.200 mol dm−3 HNO2 with 800 cm3 of 0.0625 mol dm−3
sodium nitrite, NaNO2.
i. Calculate the pH of the buffer solution.
Give your answer to two decimal places.
ka = 4.69 × 10−4
and the answer is 3.43 ✔

But how?

Reply 3

Jam.123

14

Original post by grace10101

why do you work out the moles instead of using the initial concentrations. I can't remember why