ACID-BASE TITRATION
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Experimental procedure used to establish the concentration of an acidic or basic solution when
the values are unknown.
The concentration of one solution is determined by quantitatively observing its reaction with a
solution of known concentration (standard solution).
The goal is to find the point at which the number of moles of the standard solution is
stoichiometrically equal to the original number of moles of the unknown solution (the equivalence
point).
The end-point of the titration occurs when the indicator changes colour. The indicator is chosen
so that it matches its equivalence point.
Problem:
What volume of 0.20 M soldium hydroxide is required to neutralize a 25.0 mL solution of 0.010 M
sulphuric acid?
Strategy: find the balanced chemical equation and find the moles of the acid.
2 NaOH + 1 H2SO4  Na2SO4 + 2 H2O
Solution:
nA = M x V
nA = _____________________
nA = ___________ mol H2SO4
since NaOH and H2SO4 are in a 2:1 ratio
nB = _______________ mol NaOH
VB = nB/M
VB =
mol
mol/L
VB = ______________mL H2SO4
Shortcut:
nA = nB
MAVA = MBVB
(0.020 M)(25 mL) = (0.20M) x
x = _______ mL
(caution – for the above calculation you must double the above molarity if it were a diprotic acid)