Answer:
0.43.
Explanation:
In order to solve this question we will need the an equation called Henderson-Hasselbalch Equation. The Henderson-Hasselbalch Equation can be represented by the reaction below;
pH= pKa + log ( [ A^- ] / [ HA] ).
Where HA is the acetic acid and A^- is the Acetate ion
We are given the pH value to be = 4.38 and the ka to be = 1.76×10^–5. So, we will use the value for the ka to find the pKa through the formula below.
pKa = - log ka.
Therefore, pKa = - log( 1.76×10^–5).
pKa= 4.75 + log
So,
4.38 = 4.75 + log ([ A^-] / [HA]).
4.38 - 4.75 = log ( [ A^- ] / [ HA] ).
( [ A^- ] / [ HA] ) = 10^- 0.37.
( [ A^- ] / [ HA] ) = 0.42657951880159265.
( [ A^- ] / [ HA] )= 0.43.
