Problems for Precipitation Titration and to make
you think about chemcial equations.
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4 V2(SO4)3 + ClO4-
4 H2O ® Cl-, + 8 VO2+
+ 8 H+ .
A 1.000 liter sample of sea water was evaporated to
a small volume and treated with an excess of sodium tetraphenylboron. The
precipitated tetraphenylboron was filtered and then redissolved in acetone.
The analysis was completed by a Mohr titration that required 34.32 mL of
0.03875 M AgNO3. Calculate the parts per million of potassium in the sea
K+ + NaB(C6H5)4®
KB(C6H5)4(s) + Na+ ; Ag+
AgB(C6H5)4(s) + K+
The monochloroacetic acid (ClCH2COOH, MW
= 94.5) preservative in a 100.0 mL sample of carbonated beverage was extracted
into diethyl ether and then returned to aqueous solution as ClCH2COO-
with 1 M NaOH. This aqueous extract was acidified and treated with 50.00
mL of 0.4231 M AgNO3. The reaction is
ClCH2COOH + Ag+ + H2O ®
HOCH2COOH + H+ + AgCl(s) .
After filtration of the AgCl titration of the filtrate
and washings required 12.53 mL of an NH4SCN solution. Titration
of a blank taken throught the entire process used 23.75 mL of the NH4SCN.
Calculate the weight in milligrams of the ClCH2COOH in the sample.
NH4SCN + AgNO3 ®
AgSCN(s) + NH4NO3 .
A 4.000 gram sample of KCl and KClO4 and inert materials
was dissolved in sufficient water to give 250 mL of solution. A 50 mL aliquot
required 41.00 mL of 0.07500 M AgNO3 in a Mohr titration. A
25.00 mL aliquot was then treated with V2(SO4)3
to reduce the ClO4- to Cl-, following
which titration required 38.12 mL of the same silver nitrate soltuion.
Calculate the percent of KCl (74.56) and KClO4 (138.6) in the