You need to prepare a solution buffered in the range 8.6–10.6. Given that the pKa of the ammonium ion is 9.25, what is the approximate ratio of ammonia and ammonium chloride that you will require?
The answer is 2:1 (ammonia : ammonium chloride)
I'm lost :(
pKa question?
2016-02-19 9:21 pm
回答 (2)
2016-02-19 9:53 pm
NH4^+1 <--> NH3 + H^+1
Target a buffer pH mid-way between the 10.6 - 8.6 range.
Desired buffer pH = 9.6
Use the Henderson-Hasselbalch equation
9.6 = 9.25 + log([NH3]/[NH4+])
log(NH3/NH4+) = 9.6 - 9.25 = 0.35
NH3/NH4+ = 2.24
2.24 parts NH3 to 1 part NH4^+1
Target a buffer pH mid-way between the 10.6 - 8.6 range.
Desired buffer pH = 9.6
Use the Henderson-Hasselbalch equation
9.6 = 9.25 + log([NH3]/[NH4+])
log(NH3/NH4+) = 9.6 - 9.25 = 0.35
NH3/NH4+ = 2.24
2.24 parts NH3 to 1 part NH4^+1
收錄日期: 2021-04-18 14:28:14
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