Respuesta :
The formula for pH given the pKa and the concentrations are:
pH = pKa + log [a–]/[ha]
Therefore calculating:
3.75 = 3.75 + log [a–]/[ha]
log [a–]/[ha] = 0
[a–]/[ha] = 10^0
[a–]/[ha] = 1
Answer:
[tex]\frac{[A^-]}{[HA]}=1[/tex]
Explanation:
Hello,
In this case, one state the following relationship among the pH, pKa and the [a–]/[ha] ratio for the formic acid:
[tex]\frac{[A^-]}{[HA]}=\frac{Ka}{[H^+]}[/tex]
In such a way, we compute both the concentration of hydrogen ions and the acid's dissociation constant as:
[tex][H^+]=10^{-pH}=10^{-3.75}=1.78x10^{-4}M[/tex]
[tex]Ka=10^{-Ka}=10^{-3.75}=1.78x10^{-4}[/tex]
Thus, the [a–]/[ha] ratio becomes:
[tex]\frac{[A^-]}{[HA]}=\frac{1.78x10^{-4}}{1.78x10^{-4}}\\\frac{[A^-]}{[HA]}=1[/tex]
Best regards.