Question

A solution is made by mixing 0.82 grams of sodium acetate, 1 mL of 12 M acetic acid (pKa=4.76) and water to give a final volume of 1 L. ______________ evaluates the usefulness of this solution as a buffer.

Answer 1

This solution acts as an efficient buffer

Step-by-step explanation:

the pH of a buffer solution can be described like this:
`pH=pKa+log([base])/([acid])`

[acid]=[acetic acid]=
`1mL.(12mol)/(1000mL) . (1)/(1L) = 0.012M`

[base]=[sodium acetate]=
`0.82g.(1mol)/(82g) .(1)/(1l) = 0.01M`

replacing,
`pH=4.76+log(0.01M)/(0.012M) =4.84`

If we add an acid, pH will decrease a little bit and if we add a base, pH wil increase a little bit.

lets supose that we change the rate by increasing [base] to 0.1, then

`pH=4,76+log(0.1)/(0.012) = 5.68`

and now lets supose that we increase [acid] to 0.1
`pH=4.76+log(0.01)/(0.1) = 3.76`

Big changes in concentration of base or acid doesn´t produce big changes in pH, in that way the mix of sodium acetate with acetic acid is a good buffer solution.