Question

What is the ph of a buffer that is 0.6 m hf and 0.2 m naf ? the k a of hf is 6.8 × 10 −4 ?

Answer 1

pH of buffer is 2.69

Step-by-step explanation:

According to Henderson-Hasselbalch equation for a buffer consists of an weak acid (HF) and it's conjugate base (
`F^(-)`)-

`pH=pK_(a)(HF)+log((C_(F^(-)))/(C_(HF)))`

Where C stands for concentration

`pK_(a)=-log(K_(a))`

`C_(F^(-))` in 0.2 m NaF is 0.2 m

`C_(HF)=0.6m`

So,
`pH=-log(6.8* 10^(-4))+log((0.2)/(0.6))=2.69`

Answer 2

Answer is: pH value for the buffer solution is 2,69.
c(HF) = 0,6 M.
c(NaF) = 0,2 M.
Ka(HF) = 6,8·10⁻⁴.

Henderson–Hasselbalch equation: pH = pKa + log(c(NaF)/c(HF)).

pH = -log(6,8·10⁻⁴) + log (0,2 M/0,6 M).

pH = 3,17 - 0,48.

pH = 2,69.