Hydrogen and Its Compounds
Hydrogen and Its Compounds
Hydrogen and Its Compounds
com
H SO + H SO
2 5
2 4
H2SO5 + H2O
H2O2 + H2SO4
ii. Industrially H2O2 is prepared by auto oxidation of 2-alkyl anthroquinone.
2
H 2O 2 + 2 ethylanthroquinone
2-ethyl anthroquinol
O (air)
H 2 /Pd
2. Write any two oxidising properties and two reducing properties of H2O2 with equations.
Ans.
Oxidising Properties:
i. It oxidises ferrous salts to ferric salts in acidic medium.
2Fe +2(aq) + 2H + (aq) + H 2 O 2(aq)
2Fe +3(aq) + 2H 2 O (l)
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iii. . It oxidises ferrous salts to ferric salts in basic medium
2Fe +2(aq) + H 2 O 2(aq)
2Fe +3(aq) + 2OH (aq)
Reducing Properties:
i. It reduces HOCl into Cl.
HOCl + H2O2
H3O+ + Cl + O2
ii. It reduces acidified potassium permanganate tocolourless Mn+2.
2MnO4 - + 6H+ + 5H2O2
+2
3. What do you mean by hardness of water? Give the reactions in the Ion-exchange method.
Ans. A sample of water which does not give good lather with soap is known as hard water.
Hardness of water is of two types:
a) Temporary hardness (It is due to presence of bicarbonates of calcium and magnesium)
b) Permanent hardness. (It is due to presence of chlorides and sulphates of calcium and magnesium)
permutit process : Permutit is artificial zeolite. Chemically it is hydrated sodium aluminium
orthosilicate (Na2Al2Si2O8.xH2O).Calcium and magnesium ions which cause hardness in water
are replaced by sodium ions which do not cause hardness. Thus water is softened. This method is
called Ion- exchange process.
Na2Al2Si2O8.xH2O + M2+
MAl2Si2O8.xH2O + 2Na+ . Here M2+ is Ca2+ or Mg2+.
After some use, all the sodium ions in the permutit are replaced by Ca2+ or Mg2+ ions and
then it is said that permutit is exhausted. The exhausted permutit can be regenerated by soaking it
with 10% brine (NaCl solution). Chemical reaction during the revival of exhausted permutit is given
as
MAl2Si2O8.xH2O + 2Na+
Na2Al2Si2O8.x H2O + M2 .
Here: M2+ is Ca2+ or Mg2+
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4.
Ans. i) Hydrogen is widely used as an industrial fuel as its heat of combustion is higher than other
fuels like LPG, methane,petrol etc.
ii. Pollutants in combustion of Hydrogen are only the oxides of Nitrogen which are easily removed
by injecting small amount o f water in to Hydrogen cylinder. Thus it is a better fuel than petrol.
iii. It is used in Fuel cells for generating electricity.
iv. The atomic hydrogen and Oxy Hydrogen torch are used for welding purposes and for melting
platinum metal and quartz.
v. Liquid hydrogen is used as rocket fuel.
+2
c)
CaO+H2OCa (OH)2
d)
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gas PHASE
SOLID PHASE
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The production of hydrogen can be increased by reacting carbon monoxide of syngas mixture
with steam in the presence of iron chromate as catalyst.
Fe O / Cr
CO + H2O
450 C CO2 + H2
2 3
0
8. What do you mean by autoprotolysis? Give the equation to represent the auto protolysis of
water.
Ans. The self ionisation of water is called auto protolysis.
H 3O + ( aq ) + OH ( aq )
H 2O( l ) + H 2O( l )
9.
Ans. H2O has the ability to act as a Bronsted acid when dissolving alkalies and as a Bronsted base
When an acid is dissolved in it. This is due to the autoprotolysis ,
H 3O + ( aq ) + OH ( aq )
H 2O( l ) + H 2O( l )
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