Question

What molar ratio of sodium acetate to acetic acid should be used to prepare a buffer with pH = 4.5? Ka acetic acid = 1.8 x 10-5.

Answer 1

Answer: molar ratio: 0.58

Step-by-step explanation:

This is a buffer problem. We would use the equation
`pH=pKa+log((base)/(acid) )`. Since we were given Ka and pH, we can find the ratio.

pKa=-log(Ka)

pKa=-log(1.8×10⁻⁵)

pKa=4.74

Now that we have pKa, we can plug in our values and find the molar ratio. Instead of writing base/acid, let's use x.

4.5=4.74+log(x)

-0.24=log(x)

10⁻⁰⁻²⁴=x

x=0.58