ICSE Class 10 Answered

Give reason why roasting is carried out on sulphide ores and not on carbonate ores

Asked by lovemaan5500 | 17 Mar, 2018, 05:07: PM

Expert Answer

It is easier to obtain metals from their oxides (by reduction) than from carbonates or sulphides.

So before reduction can be done, the ore is converted into metal oxide.

The concentrated ores can be converted into metal oxide by calcination or roasting.

Calcination: It is the process in which a carbonate ore is heated strongly in the absence of air toconvert it into a metal oxide.

Example:When zinc carbonate is heated strongly in the absence of air, it decomposes to form zinc oxideand carbon dioxide

ZnCO subscript 3 left parenthesis straight s right parenthesis end subscript space space rightwards arrow with 400 to the power of degree straight C on top space space space ZnO subscript left parenthesis straight s right parenthesis end subscript space plus space CO subscript 2 left parenthesis straight g right parenthesis end subscript

Roasting: It is the process in which a sulphide ore is strongly heated in the presence of air to convert it into a metal oxide.

This is done in case of sulphide ores so as to remove sulphur in the form of SO₂ and to obtained corresponding metal oxide.

2 ZnS subscript left parenthesis straight s right parenthesis end subscript space plus space 3 straight O subscript 2 left parenthesis end subscript subscript straight g right parenthesis end subscript space rightwards arrow with 800 to the power of degree straight C on top space space 2 ZnO subscript left parenthesis straight s right parenthesis end subscript space plus space 2 SO subscript 2 space subscript left parenthesis straight g right parenthesis end subscript

Answered by Varsha | 17 Mar, 2018, 06:05: PM

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