Gravimetric Analysis
gravi – metric
(weighing - measure)
Gravimetric Analysis
Gravimetric Analysis: is analytical technique based on the measurement
of mass
Steps of Gravimetric Analysis
1) Formation of precipitation
2) Isolation of precipitation
3) Determination of precipitation
We are interested in knowing the purity of sample
of NaCL obtained from seawater to do so we need
To determine expermintally the precent by mass of
CL in NaCL
A + B → C↓ + D
precipitation
AgNO3(aq) + NaCl(aq) → AgCl (s)↓ + NaNO3(𝑎𝑞 )
Precipitation:


first we would accuratly weigh out a sample NaCL
and dissolve in water (0.5662g)
Add enough ( AgNO3 aq) to the NaCL aq to cause the
precipitation of all the CL- ions present in solution in
solution (AgCL )
Filter precipitation
 Dry precipitation
 Weigh precipitation (1.0882)

dissolved
components
sample
precipitating agent
0.5662-g sample of an ionic compound containg
chloride ions and an unknown metal is dissolved in
water and treated with an excess of AgNO3. IF 1.0882
g of AgCL precipitate forms what is percent by mass
of CL in original compound
% CL =
% CL =
𝐴𝑇𝑂𝑀𝐼𝐶 𝑀𝐴𝑆𝑆 𝑂𝐹 𝐶𝐿
𝑀𝑂𝐿𝐸𝐶𝑈𝐿𝐴𝑅 𝑀𝐴𝑆𝑆 𝑂𝐹 𝐴𝑔𝐶𝐿
35.45
143.4
X100
X1OO= 24.72%
MASS OF CL = 0.42 X 1.0882 =
0.269
% CL =
0.27
0.566
X100 = 47.51%