A chemist needs Ph 4 of a buffer solution of HNO2 and NaNO2, Ka for HNO2 = 4x10^-4, conc for both are 0.25 moldm-3, what volumes would you use for both in a 250cm3 buffer?
Got this question on a past paper and just cant figure it out...
A chemist needs Ph 4 of a buffer solution of HNO2 and NaNO2, Ka for HNO2 = 4x10^-4, conc for both are 0.25 moldm-3, what volumes would you use for both in a 250cm3 buffer?
Got this question on a past paper and just cant figure it out...
(answer is 200cm3 NaNO2, 50cm3 HNO2)
So you just need to work out the ratio of moles of each needed in the buffer.
so the salt concentration has to be 4 x the weak acid concentration. As the two solutions are the same concentration then you have to mix four volumes of salt with 1 volume of acid.
A chemist needs Ph 4 of a buffer solution of HNO2 and NaNO2, Ka for HNO2 = 4x10^-4, conc for both are 0.25 moldm-3, what volumes would you use for both in a 250cm3 buffer?
Got this question on a past paper and just cant figure it out...
(answer is 200cm3 NaNO2, 50cm3 HNO2)
I understand how you work out the ratio of NO2- concentration and HNO2 concentration using your ka and H+ concentration. But, why do you divide the 250cm3 by 5? Isn't five parts the total concentration so why would you divide the volume by the total concentration?! This is so mathsy its so confusingggg I thought you have to work out moles since they gave cocentration to then work out volume.
so the salt concentration has to be 4 x the weak acid concentration. As the two solutions are the same concentration then you have to mix four volumes of salt with 1 volume of acid.
I understand how you work out the ratio of NO2- concentration and HNO2 concentration using your ka and H+ concentration. But, why do you divide the 250cm3 by 5? Isn't five parts the total concentration so why would you divide the volume by the total concentration?!
This is so mathsy its so confusingggg I thought you have to work out moles since they gave concentration to then work out volume