OXYGEN AND ITS COMPOUND
Oxygen, the first element in group vi of periodic table has eight electrons which are distributed in orbital as follows
It forms a wide range of ionic and covalent compound and it is the only element of group VI which forms multiple bonds with itself.
LABORATORY PREPARATION OF OXYGEN
Thermal decomposition of potassium trioxochlorate(v) (KClO3): KClO3, when heated releases all of its oxygen in the presence of MnO2 as catalyst.
2KClO3 MnO2 2KCl(s) + 3O2(g)
Decomposition of hydrogen peroxide H2O2: H2O2 decompose in the presence of a catalyst, MnO2, to liberate oxygen without heating.
2H2O2(l) MnO2 2H2O(l) + O2(g)
INDUSTRIAL PREPARATION OF OXYGEN
Oxygen is prepared on a large scale by fractional distillation of air.
Oxygen is then dried, compressed, stored in steel cylinder.
Properties of Oxygen
It is a colourless, odourless and neutral gas.
It is slightly soluble in water
It is slightly denser than air
It has a low boiling point of -1830C (77K)
This makes it difficult to liquefy oxygen.
Oxygen solidifies at -2250C (48K)
Chemical properties of Oxygen
With metals: Oxygen reacts with metals to give basic oxides.
4Na(s) + O2(g) 2Na2O(s)
2Ca + O2(g) 2CaO
When sodium and potassium are heated in a plentiful supply, higher oxides are formed instead of the basic oxide.
4Na(s) + 2O(g) 2Na2O2
4K(s) + 2O2(g) 2K2O2
Others metals that react/burn in oxygen are:
2Mg + O2(g) 2MgO
3Fe(s) + 2O(g) FeO.Fe2O3
With Non-Metals: Oxygen combines with non-metal to form acidic oxide.
S(s) + O2(g) SO2
P4(s) + 3O2(g) P4O6(s)
P4(s) + 5O2(g) P4O10(g)
C(s) + O2(g) CO2(g)
CH4 + 2O2(g) CO2(g) + 2H2O(g)
Test for Oxygen
Oxygen rekindles a glowing splint of wood. Nitrogen(I)oxide is the only gas that has similar chemical test with oxygen.
Uses of Oxygen
Step 1: The teacher introduces the lesson to the students by asking them to write electronic configuration of oxygen
Step 2: The teacher explains the preparation of oxygen
Step 3: The teacher explains the properties of oxygen
Step 4: Students are allowed to ask questions on what they have learnt for clarity
Step 5: Teacher copies note on chalkboard while the students copies
EVALUATION: How do you prepare oxygen industrially?
Mention 3 properties of oxygen
ASSIGNMENT: List the types of oxides with suitable examples