What mass of sodium benzoate should be added to…?

What mass of sodium benzoate should be added to 150.0 mL of a 0.16 M benzoic acid solution in order to obtain a buffer with a pH of 4.30?

Answer 1

Ka = 6.3 x 10^-5
pKa =4.2
4.30 = 4.2 + log [C6H5COO-]/ [C6H5COOH]

10^0.1 =1.26 = [C6H5COO-]/ 0.16

[C6H5COO-] = 0.202 M
moles C6H5COO- = 0.202 x 0.150L=0.0303

Mass = 0.0303 mol x 144 g/mol=4.36 g

Answer 2

Mass Of Sodium Benzoate

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