Chemistry
Explain with reasons:
Roasting is carried out on sulphide ores and not on carbonates ores.
Answer
Roasting is done in presence of air and provides oxygen to metal sulphides, which is required to convert them to metallic oxide and SO2. Whereas, carbonate is changed to oxide by loss of CO2, which occurs in the absence of air and when heated to a high temperature. Hence, roasting is not done on carbonates.
Related Questions
(a) A to F below relate to the source and extraction of either zinc or aluminium:
A. Bauxite
B. Coke
C. Cryolite
D. Froth floatation
E. Sodium hydroxide solution
F. Zinc blende
(i) Write down the three letters each from the above list which are relevant to
- Zinc
- Aluminium
(ii) Fill in the blanks using the most appropriate words from A to F.
The ore from which aluminium is extracted must first be treated with …………… so that pure aluminium oxide can be obtained.
Pure aluminium oxide is dissolved in …………… to make a conducting solution.
(iii) Write the formula of cryolite.
Explain with reasons:
In the electrolytic reduction of alumina, the graphite anode is gradually consumed.
or
Why the anode has to be replaced from time to time in this process?
Explain with reasons:
Carbon can reduce lead oxide but not aluminium oxide.
Explain with reasons:
Electrolytic reduction is done to obtain aluminium.