92 THE THEORY OF IONIZATIONthe precipitate has redissolved. The object of the rest of this
experiment is to show that a very appreciable excess of NH 4 OH
is necessary to keep AgCl from reprecipitating. Add 6N HNO 3
1 drop at a time by means of a stirring rod until a precipitate
which fails to redissolve with shaking just appears. With the
thumb over the mouth of the test tube, shake so that any drops
of reagent clinging to the sides of the tube are completely mixed
into the suspension. Remove the thumb and note whether the
odor of ammonia can be detected.
IONIC DISPLACEMENTS- Electromotive Series of the Metals, (a) Place a few
pieces of zinc in 5 cc. of 0.2 N solution of copper sulphate, shake
the mixture frequently, and after about 15 minutes withdraw
1 cc. of the solution and test it for copper and for zinc ions, apply-
ing the information obtained from the preceding experiments.
If any copper ions are still present let the remainder of the mixture
stand for 15 minutes more with frequent shaking, and repeat the
test. Continue until you have reached a conclusion as to whether
copper ions can be completely displaced from solution by zinc.
(6) Repeat (a) using 5 cc. of about 0.5 N CuSO 4 solution and
some clean pieces of iron wire.
(c) Again repeat (a) using 5 cc. of 0.1 N AgNO 3 solution and
some clean pieces of copper wire.
(d) Recall (or find out by experiment, if preferred) the be-
havior of silver, copper, iron, and zinc with hydrochloric acid or
dilute sulphuric acid. Make a list of these metals, including hy-
drogen, in the order of their ionizing potential.
HYDROLYSIS- Dissolve about 0.5 gram each of ferric chloride, sodium
chloride, and sodium carbonate in a little water, and test each
solution with red and blue litmus.
Explain the relation of hydrolysis to the observed results.
Are the reactions of hydrolysis complete? If not, explain why. - Hydrolysis a Reversible Reaction, (a) To a solution made
by dissolving 0.5 gram of solid ferric chloride in 10 cc. of water
add powdered calcium carbonate. How is the extent of the
hydrolysis of ferric chloride affected by the calcium carbonate?