Chemical Properties of Hydrogen with equations
Chemical Properties of Hydrogen:
1. Decomposition of molecular Hydrogen (H2)
Molecular hydrogen contains stable covalent
bonding and is relatively inert at ordinary conditions. Its bond dissociation
energy is 104 K.cals/mol.
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H
— H
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H
+ H rH
= 104 K.cals/mol. i.e +435 KJ/,mol.
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Q.
Show hydrogen is a good reducing agent:
2. As a reducing Agent
Hydrogen shows greater affinity for oxygen and
reduces many metal oxides into free metals.
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CuO(s)
+ H2(g)
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Cu(s)
+3H2O(g)
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WO3(s)
+ 3H2(g)
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W(s)
+ 3H2O(g)
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1. Hydrogenation Reaction:
The addition of hydrogen into other molecular
compounds called hydrogenation reaction. When molecular compounds and Hydrogen
are heated in the presence of Pt or Pd or Ni and other crystals they give
addition products.
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ZnO/Cr2O3
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1.
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CO(g)
+ 2H2(g)
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CH3
– OH(l)
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400oC /high
presusure
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Methyl
Alcohol
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Ni
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2.
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CH2
= CH2(s) + H2(g)
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CH3
– CH3
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Ethene
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400oC
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Ethane
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Ni
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3.
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Edible
oils (liquid)+ H2(s)
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Vegetable
Ghee (Solid)
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Un
saturated
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High Temp.
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Saturated
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2. Reaction with metals:
Alkali
metals like Na, K etc. and alkaline earth metals like Ca, Ba react with
hydrogen on heating to form ionic hydrides.
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200 oC
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1.
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2Na(s)
+ H2(g)
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2Na+H
–(s)
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Sodium
Hydride
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200 oC
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2.
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Ca(s)
+ H2(g)
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Ca+2
H2(s)–
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Calcium
hydride
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3. Reaction with non-metals:
Hydrogen
reacts with many non-metals under different conditions to form addition
products.
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500 oC/200dtm
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1.
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N2(g)
+ 3H2(g)
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2NH3
(g)
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Fe2O3/K2O
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Sunlight
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2.
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H2(g)
+Cl2(g)
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2HCl(g)
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450 oC
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3.
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H2(g)
+S(s)
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H2S(g)
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