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Study of the First Element - Hydrogen — CHEMISTRY STD 9 — Question

ICSE BoardEnglish MediumSTD 9CHEMISTRYStudy of the First Element - Hydrogen5 Marks
Question
How can these impurities be removed?
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Answer

  1. The impurities can be removed from hydrogen by passing it through
  1. Silver nitrate solution to remove arsine and phosphine.
$AsH_3+ 6AgNO_3→ Ag_3As + 3AgNO_3+ 3HNO_3$
$PH_3+ 6AgNO_3→ Ag_3P + 3AgNO_3+ 3HNO_3$
  1. Lead nitrate solution to remove hydrogensulphide.
$Pb(NO_3)_2+ H_2S → Pbs + 2HNO_3​​​​​​​$​​​​​​​
  1. Caustic potash solution to remove sulphur dioxide, carbon dioxide and oxides of nitrogen.
$SO_2+ 2KOH → K_2SO_3+ H_2O$
$CO_2+ 2KOH→ K_2CO_3+ H_2O$
$2NO_2+ 2KOH →KNO_2+ KNO_3+ H_2O​​​​​​​$​​​​​​​
  1. 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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