114 THE THEORY OF IONIZATION
Formation of Volatile Products. When a product of a reaction
is volatile it has a tendency to escape from the sphere of action,
and the progress of the reaction towards the formation of this
product is favored.
When all the products of a reaction taking place in solution are
soluble, their concentration will increase as the reaction pro-
gresses, until a point of equilibrium is reached, at which point the
products react with each other to form the original substances
again, and the backward reaction takes place with sufficient
rapidity just to offset the effect of the forward reaction.
But with the escape of one of the products as a gas, and thereby
the removal of this product from the sphere of action, the reverse
reaction is eliminated, and the forward reaction is thus enabled
to run to completion.
PROBLEMS
Describe the observable effects and write the fully ionized equa-
tions for the following cases:
- HNO 3 + NaOH.
- HC 2 H 3 O 2 + NH 4 OH.
- Mg(OH) 2 (solid) + HNO 3.
- CuO (solid) + H 2 SO 4.
- H 2 S (gas) + NaOH.
- NH 3 (gas) + HC1.
- H(C 7 H 6 O 2 ) (solid) + NaOH.
Benzoic acid H (C 7 H 6 O 2 ) is a sparingly soluble solid, and a little
stronger than acetic acid. - K(C 7 H 6 O 2 ) + HC1.
- Ca(C 2 H 3 O 2 ) 2 + HN0 3. Note odor.
- (NH 4 ) 2 SO 4 + NaOH. Note odor.
- NH4CI (in excess) + Ca(OH) 2 (solid). Note odor.
- CaCO 3 (solid) + HN0 3.
- CaCO 3 (solid) + HC 2 H 3 O 2.
- FeS (solid) + HC1.
- MgCl 2 + Na0H.
- MgCl 2 + NH 4 OH.
- MgCl 2 + NH4CI + NH4OH.
- Ca(OH) 2 (solid) + FeCl 3.
- Ca(OH) 2 (saturated solution) + CO 2 (gas, in moderate
amount and then in excess).