0.050 mol tris + 0.025 mol HCl tris buffer pH (pKb 5.92)

0.050 mol tris + 0.025 mol HCl tris buffer pH (pKb 5.92)

 

 

“Tris” is short for tris(hydroxymethyl)aminomethane.

This weak base is widely used in biochemical research

for the preparation of buffers.

It offers low toxicity and a pKb of 5.92 making it convenient

for the control of pH in clinical applications.

A buffer is made by mixing 0.050 mol of tris

with 0.025 mol of HCl in a volume of 2.00 L.

Calculate the pH of the solution.

 

 

A buffer is prepared by mixing 0.050 mol of tris

with 0.025 mol of HCl in a volume of 2.00 L.

Compute the pH of the solution.

 

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[tris buffer의 핵심 원리]

약산-강염기 적정에서,

당량점 이전에서는

약산과 짝염기가 동시에 존재하므로,

완충 용액이 형성된다.

( 참고 https://ywpop.tistory.com/2742 )

 

 

 

B(aq) + HCl(aq) → BH^+(aq) + Cl^-(aq)

가한 HCl의 몰수만큼, (0.025)

약염기의 몰수는 감소(소모), (0.050 – 0.025 = 0.025)

짝산의 몰수는 증가(생성). (0.025)

 

 

 

Henderson-Hasselbalch 식

pOH = pKb + log([짝산]/[약염기])

( 참고 https://ywpop.tistory.com/1926 )

 

= 5.92 + log(0.025 / 0.025)

= 5.92

( 참고: 몰농도 대신 몰수 https://ywpop.tistory.com/13452 )

 

 

 

pH = 14 – 5.92 = 8.08

 

 

 

답: pH = 8.08

 

 

 

 

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