Question
How many moles of NaOH must be added to 1.0 L of 1.4 M HC2H3O2 to produce a solution buffered at each pH?
(a) pH = pKa mol
(b) pH = 3.07 mol
(c) pH = 5.15 mol
(a) pH = pKa mol
(b) pH = 3.07 mol
(c) pH = 5.15 mol
Answers
DrBob222
Use the Henderson-Hasselbalch equation.
First find moles acetic acid. M x L = moles.
.......CH3COOH + OH^- ==>CH3COONa + H2O
start...moles.... 0.......0
change..-x........+x........+x
final..moles-x.....0......0+x
Then substitute into the HH equation and solve for x. After, I always like to check it by calculating the moles acetate and moles acetic acid remaining, plug into the HH equation and see if it gives the correct pH.
First find moles acetic acid. M x L = moles.
.......CH3COOH + OH^- ==>CH3COONa + H2O
start...moles.... 0.......0
change..-x........+x........+x
final..moles-x.....0......0+x
Then substitute into the HH equation and solve for x. After, I always like to check it by calculating the moles acetate and moles acetic acid remaining, plug into the HH equation and see if it gives the correct pH.