Synthetic Inorganic Chemistry

STANDARDIZATION OF SOLUTIONS 75

The gram equivalent weight of a base is the weight in grams re-
quired to neutralize one gram atomic weight of hydrogen in an
acid. In the reaction HC1 + NaOH —» H 2 O + NaCl one mole
of NaOH exactly neutralizes one mole of HC1. Therefore, 40
grams of NaOH are equivalent to 36.5 grams of HC1. If calcium
hydroxide is used, the equation Ca(0H) 2 + 2HC1 -> 2H 2 O +
74
CaCl 2 shows that the gram equivalent weight is -~-> or 37

grams.
The gram equivalent weight of salts is obtained in the same way.
In the two neutralization reactions mentioned above, one mole of
NaCl and one-half mole of CaCU are each equivalent to one mole

of HC1. The equivalent weights are * grams of NaCl and -„-
I Zi
grams of CaCl 2.
Normal Solution. A normal solution contains one equivalent
weight of the dissolved substance in 1 liter of solution. In a liter
of normal hydrochloric acid (written IN HC1) there are -—^

grams of hydrogen chloride and enough water to make 1 liter of
solution. A liter of 6iV HC1 contains 6 times as much acid,

z—— grams of hydrogen chloride in a liter of solution. Since

it is not convenient to measure or weigh hydrogen chloride gas in
making solutions, a concentrated solution of known composition
is diluted to the desired normality. The concentrated acid of
commerce is approximately 12 N, and, to make a 1N solution from

it, ' cc. are diluted to 1 liter. A liter of normal sulphuric acid

98
contains -=- grams of the pure acid. In practice, concentrated

sulphuric acid, which is approximately 36 N, is diluted to give the
desired normality. A normal solution of sodium hydroxide con-
tains 40 grams of base in a liter of solution; one of Ba(0H) 2 con-
171 4
tains —~- grams of base in 1 liter of solution.

From this discussion it is obvious that 1 liter or' 1N acid will
neutralize exactly 1 liter of liV base. It follows that a given
volume of a liV solution of any acid will exactly neutralize an
equal volume of a 1N solution of any base.