Answer to Question #135479 in General Chemistry for emma

Question

A solution is made up by adding 12.56g of sodium benzoate to 250.0mL of water. Calculate the pH of the resulting solution.

Answer 1

$C_6H_5COO^-+H_2O\to C_6H_5COOH+OH^-$

$K_b=\frac{[C_6H_5COOH][OH^-]}{[C_6H_5COO^-]}=1.6\times10^{-10}$

$[C_6H_5COO^]=\frac{12.56}{144}=0.087M$

$K_b=\frac{C\times C}{0.087}=1.6\times10^{-10}$

$C=[OH^-]=0.37\times10^{-5}M$

$pOH=-log[OH^-]=5.43$

$pH=14-pOH=14-5.43=8.57$