Buffers STAT! You are working in a high-powered clinical biochemistry lab. The chief scientist rushes in and announces, “I need 500 ml if .2 M acetate, pH 5.0. STAT!” You have sold anhydrous sodium acetate (MW = 82 g/mol) and a solution of 1M acetic acid. Describe how you would make the buffer.
Answered Essay: Buffers STAT! You are working in a high-powered clinical biochemistry lab. The
Expert Answer
From Handerson equation, pH of buffer solution is given by
pH = Pka + log[salt]/[acid]
Given that, pH = 5.0
pKa of acetic acid = 4.74
[sodium acetate] = 0.2 M
[Acetic acid] = 1.0 M
To get a 500mL of pH of 5.0 buffer solution using 0.2M CH3COONa and 1M CH3COOH, it is required to take in the following ratio
pH = 4.74+log(0.2*450/1*50) = 5.0
It is required to make a 0.2 M of 450 mL sodium acetate solution
The weight of sodium acetate required to make 0.2M of 450 mL solution is given by
M = (wt/mol.wt)(1000/V(mL))
0.2 = (wt./82)(1000/450) = 7.38 g
