Preparation of Dihydrogen, H2
Laboratory Preparation of Dihydrogen
- It is usually prepared by the reaction of granulated zinc with dilute hydrochloric acid.
- It can also be prepared by the reaction of zinc with aqueous alkali.
Commercial Production of Dihydrogen
- By the electrolysis of acidified water
- Form water gas (Bosch process)
- From steam (Lane’s process) super-heated steam is passed over iron filings heated to about 1023-1073 k when hydrogen is formed.
- Highly pure (> 99.95 %) dihydrogen is obtained by electrolyzing warm aqueous barium hydroxide solution between nickel electrodes.
- From hydrocarbons by partial oxidation
- It is also obtained as a by-product in the manufacture of NaOH and chlorine by the electrolysis of brine solution.
During electrolysis, the reactions that take place are
Properties of Dihydrogen
- Dihydrogen is a colourless, odourless and tasteless gas.
- It is a combustible gas.
- It is insoluble in water.
- It is lighter than air.
Chemical Properties of Dihydrogen
- Reaction with halogens: It reacts with halogens, X2 to give hydrogen halides. HX.
(F can react with hydrogen in dark also, iodine requires a catalyst)
- Reaction with dioxygen:
The reaction is highly exothermic.
- Reaction with dinitrogen: With dinitrogen to form ammonia
- Reaction with metals: Here H2 acts as oxidising agent.
Where (M = alkali metal)
- Reaction with metal ions and metal oxides: It reduces some metal ions in aqueous solution and oxides of metals (less active than iron) into corresponding metals
- Reaction with organic compounds: It reacts with many organic compounds in the presence of catalysts to give useful hydrogenated products of commercial importance.
- Hydrogenation of vegetable oils using nickel as catalyst gives edible fats (margarine and Vanaspati ghee).
- Hydroformylation of olefins yields aldehydes which further undergo reduction to give alcohols.
Use of Dihydrogen
- It is used in the manufacture of CH3OH.
- It produces temperature of 2850oC and oxy-atomic hydrogen flame produces a temperature of 4000oC, so it is used in oxy-hydrogen flame.
- The largest single use of H2 is in the synthesis of NH3 which is used in the manufacture of HNO3 and fertilizers.
- Liquid hydrogen (LH2) is used as rocket fuel.
- H2 is used as a reducing agent in extraction of metals.
- H2 is used in fuel cell for generating electrical energy.
- Hydrogen is used in the manufacture of synthetic petrol.
(By heating H2 with coal and heavy oils under very high pressure in the presence of catalyst).
We are sorry that this post was not useful for you!
Let us improve this post!
Tell us how we can improve this post? Please mention your Email so that we can contact you for better feedback.