Chemistry
Give reasons for the following:
Copper does not displace hydrogen from dilute hydrochloric acid, but zinc does.
In the preparation of hydrogen by electrolysis of water - the distilled water used is acidified.
In the laboratory preparation of hydrogen from zinc and dilute hydrochloric acid the zinc used is granulated zinc.
In Bosch process - the final gaseous products are passed through caustic potash [KOH] soln.
The reaction of chlorine with hydrogen sulphide is deemed a redox reaction.
Hydrogen
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Answer
In the metal reactivity series, copper (Cu) is below hydrogen but zinc (Zn) is above hydrogen. Hence, copper does not displace hydrogen from dilute hydrochloric acid, but zinc does.
Pure water is almost a non-electrolyte and will not normally conduct electricity. It consists almost entirely of molecules. It can be electrolytically decomposed by addition of traces of dil. H2SO4 which dissociates as: H+1 and SO4-2 and help in dissociating water into H+ and OH- ions.
Granulated zinc contains traces of impurities, which has a slight catalyzing effect on the reaction and speeds it up.
CO2 is removed by dissolving mixture in caustic potash solution.
2KOH + CO2 ⟶ K2CO3 + H2OHydrogen sulphide reacts with chlorine as per the below equation:
H2S + Cl2 ⟶ 2HCl + S
Here, H2S is oxidised to S and Cl2 is reduced to HCl, at the same time. Hence, it is a redox reaction.
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Related Questions
With reference to the equation:
Cl2 + H2S ⟶ 2HCl + S
pertaining to a redox reaction - select the correct answer in each case -
(a) Chlorine is oxidised/reduced to HCl.
(b) Hydrogen sulphide is oxidised/reduced to sulphur since the reaction involves addition/removal of hydrogen.
(c) Chlorine acts as an oxidising/reducing agent.
Give balanced equations for the following conversions:
Zinc to sodium zincate - using an alkali.
Acidified water to hydrogen - by electrolysis.
Water gas to hydrogen - industrially.
Iron [III] oxide to iron - using hydrogen.
Nitrogen to a basic gas - using hydrogen.
Select the correct answer from A, B, C, D or E for each statement given below:
A: Nickel
B: Sodium
C: Iron
D: Iron [III] oxide
E: Magnesium oxide
A metal which reacts with water to give a metallic hydroxide & liberate hydrogen.
The metallic compound used as a catalyst in Bosch process.
The metal used as a catalyst in hydrogenation of oils.
The metal which reacts with steam liberating hydrogen & the reaction is reversible.
The metallic compound formed when a metal above aluminium in the activity series reacts with steam.
Select the correct answer from the choice in bracket to complete each sentence.
The acid …………… [dil.H2SO4, dil. HNO3, dil. HCl] is not used in the laboratory preparation of hydrogen, using zinc and an acid.
In Bosch process the catalytic reduction of steam to hydrogen is carried out by …………… [CO2, CO, C].
A foul smelling gas formed when hydrogen reacts with a molten non-metal is …………… [hydrogen chloride, hydrogen sulphide, ammonia].
The product formed on combustion of hydrogen in air is …………… [water gas, water, producer gas].
The gas which has now replaced hydrogen in air balloons is …………… [argon, helium, neon]