Question

A buffer solution is prepared by adding 275 mL of .676 M of HCl to 500 mL of .525M sodium acetate. What is the pH of this buffer?

Answer 1

-6.15

Explanations

The formula for calculating the pH of a buffer is expressed as

`pH=pka+log([salt])/([acid])^`

pka of the hydrochloric acid = -6.3

Calclate the moles of the HCl and sodium acetate

`\begin{gathered} moles=molarity* volume \\ moles\text{ of HCl=0.676M}*0.275 \\ moles\text{ of HCl=0.1859moles} \end{gathered}`

Calculate the moles of sodium acetate (salt)

`\begin{gathered} moles\text{ of sodium acetate=0.525M}*0.500 \\ moles\text{ of sodium acetate=0.2625moles} \end{gathered}`

Substitute the given parameters into the formula

`\begin{gathered} pH=pka+log\frac{[0.2625\text{/v}]}{[0.1859\text{/v}]} \\ pH=-6.3+log1.4121 \\ pH=-6.3+0.1498 \\ pH=-6.1502 \end{gathered}`

Hence the pH of this buffer is approximately -6.15