Assume you have 4 weak acids: HA (pKa = 4), HB (pKa = 4.5), HC (pKa = 4.8), HD (

Question

Assume you have 4 weak acids: HA (pKa = 4), HB (pKa = 4.5), HC (pKa = 4.8), HD (pKa = 5.5). If you want to prepare a pH 4.7 buffer, what acid and it’s cesium salt are the best? If the concentration of the acid is 0.1M, what is the concentration of the cesium salt? Assume you have 4 weak acids: HA (pKa = 4), HB (pKa = 4.5), HC (pKa = 4.8), HD (pKa = 5.5). If you want to prepare a pH 4.7 buffer, what acid and it’s cesium salt are the best? If the concentration of the acid is 0.1M, what is the concentration of the cesium salt?

Explanation / Answer

buffer is most effective when pH is equal to the value of pKa
Here pH is closest to pKa value of HC
So, HC will suit the need better

USE:
pH = pKa + log {[salt]/[acid]}
4.7 = 4.8 + log {[salt]/0.1}
log {[salt]/0.1} = -0.1
[salt]/0.1 = 0.7943
[salt] = 0.079 M
Answer:
HC
0.079 M

Feel free to comment below if you have any doubts or if this answer do not work

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