wat03 Hydrochloric acid
from "hydrochloric acid gas" and water
Sulfuric
acid is very corrosive:TEACHER EXPERIMENT!
First photo: Add 5 drops of
conc. sulfuric acid to a spatula of table salt (NaCl) to a 4-ml vial.
*
Second photo:
* Close this vial by a stopper connected
to the mouth of a second vial
by an infusion tube. It has to end above the liquid!
* Threequater fill the second
vial with yellow solution of universal indicator. (The
vials are connected by a piece of wire).
Observations
1. Gas bubbles leave the salt.
2. The surface of the water in the right vial shows a red colour.
3. The red liquid sinks to the
bottom.
Explanations
1. Hydrogen chloride
gas [HCl(g)] is formed by an acid base reaction
between sulfuric acid and chloride ions:
2 NaCl(s)
+ H2SO4(l) ------------> 2 HCl(g) +
Na2SO4(s)
2. Hydrogen chloride gas and
water form hydrochloric acid [HCl(aq)] in another acid
base reaction:
2 HCl(g) +
H2O(l) ------------> 2 HCl(aq)
3. Hydrochloric acid
has a higher density than water.
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publication: 16.10.2001................................last
modification: 24.06.2010