In: Chemistry
Methanoic acid has a Ka=1.6X10-4. Calculate the pH of the final solution when 23.90 mL of 0.100M NaOH is added to 25.00 mL of 0.100 M methanoic acid
Ka = 1.6 x10^-4
NaOH = 23.90 ml of 0.100M
number of moles of NaOH = 0.100M x 0.02390L = 0.00239 moles
Methanoic acid = 25.00ml of 0.100M
number of moles of Methanoic acid = 0.100M x 0.02500L = 0.0025 moles
Ka = 1.6 x 10^-4
-log(Ka) = -log(1.6 x10^-4)
Pka = 3.79
Methanoic acid = HCOOH
HCOOH + NaOH --------------------- HCOONa + H2O
Initial 0.0025 0.00239 0
change - 0.00239 - 0.00239 + 0.00239
equilibrium 0.00011 0 + 0.00239
PH = Pka + log[salt]/[acid]
PH = 3.79 + log(0.00239/0.00011)
PH = 5.13
PH of the solution = 5.13