Oxides of Hydrogen
Hydrogen atoms can react with oxygen atoms forming different
compounds. There are mainly two types, one is water and the other is
A water molecule is made up of two hydrogen atoms and one oxygen atom
joining together by covalent bonds. The shape of it is bent and its
bond angle is of 105Â°. The structure is shown below.
A hydrogen peroxide molecule consists of two hydrogen atoms and two
oxygen atoms joined together by covalent bonds. It is relatively
unstable in sunlight as repulsion exists between non-bonded electrons
in the oxygen atoms, forming free radicals easily. The structure is
Water and hydrogen peroxide have a simple molecular structure and held
by hydrogen bonds. The slightly positive charged hydrogen atom is
attracted by the lone pair electrons on the oxygen atoms.
Both water and hydrogen peroxide have a high melting point and boiling
point due to the presence of hydrogen bonds between the molecules of
them. For water at 1 atm, the melting point and boiling point is 0Â°C
and 100Â°C respectively.
Water reaches the maximum density at 4Â°C. The density of ice is lower
than that of water. The molecules are in constant motion and the
strong hydrogen bonding leads to the closed packing of water
The melting curve of water in the phase diagram has an unusual
negative slope. When the pressure of water increases, its melting
point decreases. This is because high pressure reduces the volume of
water and this is achieved by changing ice to liquid water.
Water and hydrogen peroxide are poor electrical conductors as they can
only slightly ionize in water.
2H2O(l) ï¼ H3O+(aq) + OH-(aq)
2H2O2 (aq) ï¼ H3O2+(aq) + HO2-(aq)
Water is also a good solvent due to its polar nature. It can dissolve
many ionic substances by the solvation of ions in the solution.
Moreover, it has a low viscosity and a high specific heat capacity.
(4200 J kg-1 Â°C-1)
Hydrogen peroxide is miscible with cold water and is soluble in
alcohol and ether. Although pure hydrogen peroxide is fairly stable,
it decomposes into water and oxygen when heated above about 80Â°C
Occurrence and synthesis:
Water is a naturally occurring substance and most of the earthÂ’s
surface is sea. But water from sea is impure. To obtain pure water,
simple distillation is practical.
Hydrogen peroxide can be prepared by autoxidation of
Water is involved in many chemical reactions.
Reaction with metals: Water can react with reactive metals like
potassium, sodium and calcium to forming...