Explain with reasons:
(a) In the electrolytic reduction of alumina, the graphite anode is gradually consumed.
or
Why the anode has to be replaced in this process?
(b) Roasting is carried out on sulphide ores and not on carbonate ores.
(c) Carbon can reduce lead oxide but not aluminium oxide.
(d) Electrolytic reduction is done to obtain aluminium?
(e) Why 'the food containing iron salts' should not be cooked in aluminium utensils?
Explain with reasons:
(a) In the electrolytic reduction of alumina, the graphite anode is gradually consumed.
or
Why the anode has to be replaced in this process?
(b) Roasting is carried out on sulphide ores and not on carbonate ores.
(c) Carbon can reduce lead oxide but not aluminium oxide.
(d) Electrolytic reduction is done to obtain aluminium?
(e) Why 'the food containing iron salts' should not be cooked in aluminium utensils?
a) In electrolytic reduction of alumina,oxygen gas is evolved at the anode which oxidises the carbon(graphite )anode to CO and further, to CO2 .As a result ,the graphite anode is consumed and needs to be replaced gradually.
b) In case of carbonate ores, we need to eliminate the carbonate and moisture. So, the ore is heated to high temperatures in the absence of air. Carbon, which is in its highest oxidation state, cannot be oxidised further (roasting is done convert the ore to its oxide form by addition of oxygen, in carbinate ores already there is oxygen so we don't need to add furthermore oxygen).
c) We can use carbon to reduce the oxides of metals below aluminium in the Reactivity Series. Because of this, carbon is used in the extraction of zinc, iron, and lead. Aluminum oxide is exceptionally steady and Carbon is less reactive than aluminum, hence it can't be utilized to diminish aluminum oxide to aluminum metal.
d) Aluminium can't be extracted from its ore by reduction with carbon as it is more reactive to carbon, so electrolytic reduction is done to obtain Al.
e) Aluminium is more reactive to iron so Al can displace Fe from the salts i.e aluminium will react and form new compounds which is not suitable for eating.
a) In electrolytic reduction of alumina,oxygen gas is evolved at the anode which oxidises the carbon(graphite )anode to CO and further, to CO2 .As a result ,the graphite anode is consumed and needs to be replaced gradually.
b) In case of carbonate ores, we need to eliminate the carbonate and moisture. So, the ore is heated to high temperatures in the absence of air. Carbon, which is in its highest oxidation state, cannot be oxidised further (roasting is done convert the ore to its oxide form by addition of oxygen, in carbinate ores already there is oxygen so we don't need to add furthermore oxygen).
c) We can use carbon to reduce the oxides of metals below aluminium in the Reactivity Series. Because of this, carbon is used in the extraction of zinc, iron, and lead. Aluminum oxide is exceptionally steady and Carbon is less reactive than aluminum, hence it can't be utilized to diminish aluminum oxide to aluminum metal.
d) Aluminium can't be extracted from its ore by reduction with carbon as it is more reactive to carbon, so electrolytic reduction is done to obtain Al.
e) Aluminium is more reactive to iron so Al can displace Fe from the salts i.e aluminium will react and form new compounds which is not suitable for eating.
