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Question
How can these impurities be removed?
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Solution
- The impurities can be removed from hydrogen by passing it through
- Silver nitrate solution to remove arsine and phosphine.
AsH3 + 6AgNO3 → Ag3As + 3AgNO3 + 3HNO3
PH3 + 6AgNO3 → Ag3P + 3AgNO3 + 3HNO3
- Lead nitrate solution to remove hydrogensulphide.
Pb(NO3)2 + H2S → Pbs + 2HNO3
- Caustic potash solution to remove sulphur dioxide, carbon dioxide and oxides of nitrogen.
SO2 + 2KOH → K2SO3 + H2O
CO2 + 2KOH→ K2CO3+ H2O
2NO2 + 2KOH →KNO2 + KNO3 + H2O
- A drying agent used to dry the gas. Common drying agents such as fused calcium chloride, caustic potash stick and phosphorus pentoxide remove water vapor.
So, the gas is purified and dried and then collected over mercury because mercury does not react with it.
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RELATED QUESTIONS
Indicate which of the following statement is true and which is false:
Nitric acid cannot be used to prepare hydrogen by its action on active metals.
Give reason for the following:
Nitric acid not used for the preparation of hydrogen gas?
Multiple Choice Question
In metal activity series the more reactive metals are at
FILL IN THE BLANK
Sodium liberates hydrogen when treated with cold .............
Why is granulated zinc preferred in the laboratory preparation of hydrogen?
Give a test to identify hydrogen ?
Give reason:
Apparatus for laboratory preparation of hydrogen should be airtight and away from a naked flame.
How would you show that hydrogen is lighter than air?
Starting from zinc how would you obtain hydrogen using an alkali.
[Give balanced equation & name the product formed in the case other than hydrogen].
Name a metal which will not react with the reactants above to give hydrogen.
In the laboratory preparation of hydrogen from zinc & dilute hydrocholoric acid – state a reason for the addition of traces of copper [II] sulphate to the reaction medium.
Draw neat labelled diagrams for two different experiments to prove that – hydrogen is lighter than air.
Give reason for the following:
In the laboratory preparation of hydrogen from zinc and dilute hydrochloric acid – the zinc used granulated zinc.
Complete and balance the equation:
[Laboratory method]
By action of dilute acid on zinc
Zinc - Zn + 2HCl → _____ + _____ [g]
Select the correct answer from the symbol in the bracket.
The element which forms a diatomic molecule.
The diagram represent the preparation and collection of hydrogen by a standard laboratory method.
State what difference will be seen if pure zinc is added in the distillation flask ‘X’ instead of granulated zinc.
The diagram represent the preparation and collection of hydrogen by a standard laboratory method.
State, why hydrogen is collected after all the air in the apparatus, is allowed to escape.
The diagram represent the preparation and collection of hydrogen by a standard laboratory method.
Name a gas other than hydrogen collected by the same method.
