| time
requ.: |
15 minutes. |
|
objective: |
Acid synthesis
from salts. |
| material: |
|
|
| chemicals: |
- sodium chloride
- water
- indicator solution
|
- conc. sulphuric acid
|
|
procedure 1: |
Fill the snap top vial with 5ml water, add some drops
of indicator. Observe indicator colour and conductivity result. |
|
procedure 2: |
Gas formation: Use gas generator. Fill about 0,5cm sodium
chloride in the snap top vial. Syringe 1 contains 3ml conc. sulphuric acid.
While pressing in 2ml sulfuric acid the charcoal filter is on top of
needle 2. In the gas generator hydrogen chloride is formed. Absorb it
with syringe 2 by temporarily removing the filter. |
|
procedure 3: |
Inject the gas (minimum 5cml) into the water in the snap top vial
using the needle on the syringe. Watch changes of pH and electrical conductivity. |
|
observation: |
pH sinks,
electrical conductivity rises (conductivity light signal is low!). |
|
interpretation: |
2 NaCl(s) + H2SO4
---> 2Na2SO4 +
2HCl(g)
sodium chloride sulphuric acid sodium sulphate
hydrogen chloride
HCl(g) +
aq --->
2HCl(aq)
as H3O+(aq) + Cl-(aq)
hydrogen chloride water hydrochloric
acid |
|
disposal of: |
Neutralize
sulfuric acid, then pour to sink using
much water. |
|
source: |
Barke, H.-D. et al.: One Hundred
Chemistry-Experiments to Avoid Chalk and Talk; University of Muenster,
2004. |
|
Extension: |
Similar with H2SO3,
H2CO3 |
