| |
Gas Lab Manual
Predicting Gases
We can anticipate the gas expected
from the nature of the test performed and the colour
and texture of the substance by preliminary examination.
|
Process
|
Substances
|
Gas expected
|
| 1.
Heating |
All carbonates
except Na2CO3 and K2CO3.
All hydrogen carbonates, HCO3- |
CO2
|
| Ammonium chloride,
NH4Cl |
NH3, HCl
|
| Ammonium carbonate,
(NH4)2CO3 |
NH3, CO2
|
| All nitrates, NO3-.
oxygen-rich compound, e.g. H2O2 |
O2
|
| Nitrate of metals
below sodium in the reactivity series. |
NO2
|
| 2.
Addition of dilute acid |
Carbonates, CO32- |
CO2
|
| Sulphite ion,
SO32- |
SO2 |
| Reactive metals
above Pb in the reactivity series. |
H2 |
| 3.
Addition of NaOH and heat |
Ammonium
ion, NH4+ |
NH2
|
| 4. Addition of
NaOH, aluminium foil/powder or Devarda's alloy |
Nitrate, NO3- |
NH3, H2
|
| 5. Addition of
oxidising reagent |
Concentrated hydrochloric
acid |
Cl2
|
| 6. Addition of
MnO2. |
Hydrogen peroxide,
H2O2 |
O2
|
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