Advertisements
Advertisements
प्रश्न
What is the difference between calcination and roasting?
Compare roasting and calcination.
Advertisements
उत्तर
| Roasting | Calcination | |
| (1) | The ore is heated in the excess of air. | The ore is heated in the absence of air. |
| (2) | Volatile impurities are removed as oxides (SO2, P2O5, As2O3) and the ore becomes porous and more reactive. | Moisture and organic impurities are removed and the ore becomes porous and more reactive. |
| (3) | Sulphide ores are roasted, so SO2 is given off. \[\ce{2ZnS + 3O2 ->[800^\circ-900^\circ C]2ZnO + 2SO2}\] |
Carbonate and hydrated ores are calcined and CO2 or water vapour are given off. \[\ce{ZnCO3 -> ZnO + CO2}\] |
APPEARS IN
संबंधित प्रश्न
Define the Ore.
In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?
Name the most abundant metal in the earth's crust.
Why does aluminium not corrode right through?
What is meant by the 'concentration of ore'?
Name the chemical compound which is electrolysed in molten state to obtain sodium metal. Which gas is produced in this process?
Name the gas produced when calamine ore is calcined.
Which metal is extracted from cinnabar ore?
Metals X and Y can be recovered from the anode mud left behind after the electrolytic refining of copper metal. The coins made of metal X look new even after several years of use but the coins made of metal Y lose their shine gradually and get blackened soon. When metal X is alloyed with a small amount of metal Y, it becomes hard and hence suitable for making ornaments. What are metals X and Y? Also state the colour of metal X.
Name the ore of mercury. With the help of balanced chemical equations, explain the process of extraction of mercury from its ore.
Answer the following question :
What is the difference between calcination and roasting.
If Cu, Fe, Zn, Al elements are arranged in increasing order of their reactivity then the correct order would be which of the following?
In Electrolytic reduction of alumina, Anode : _______ : : Cathode : Graphite lining
Observe the following diagram and write answers.
- Name the method.
- Write anode reaction and cathode reaction.
- Why fluorspar and cryolite are added in the mixture?
In extraction of copper, the flux used is ____________.
2 mL each of concentrated HCl, HNO3 and a mixture of concentrated HCl and concentrated HNO3 in the ratio of 3 : 1 were taken in test tubes labelled as A, B and C. A small piece of metal was put in each test tube. No change occurred in test tubes A and B but the metal got dissolved in test tube C respectively. The metal could be
Iqbal treated a lustrous, divalent element M with sodium hydroxide. He observed the formation of bubbles in reaction mixture. He made the same observations when this element was treated with hydrochloric acid. Suggest how can he identify the produced gas. Write chemical equations for both the reactions.
During extraction of metals, electolytic refining is used to obtain pure metals.
(a) Which material will be used as anode and cathode for refining of silver metal by this process?
(b) Suggest a suitable electrolyte also.
(c) In this electrolytic cell, where do we get pure silver after passing electric current?
- Given below are the steps for extraction of copper from its ore. Write the reaction involved.
- Roasting of copper (I) sulphide
- Reduction of copper (I) oxide with copper (I) sulphide.
- Electrolytic refining
- Draw a neat and well labelled diagram for electrolytic refining of copper
The given reaction shows one of the processes to extract the metals like Iron and Manganese.
\[\ce{MnO2(s) + Al(s) -> Mn(l) + Al2O3(s) + Heat}\]
Give a reason why Aluminium is preferably used in thermite reactions.
