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प्रश्न
What is the difference between calcination and roasting?
Compare roasting and calcination.
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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. \[\ce{ZnCO3 -> ZnO + CO2}\] |
संबंधित प्रश्न
Name two metals which are found in nature in the free state.
Which of the following pairs will give displacement reactions?
Give reasons.
Carbonate and sulphide ores are usually converted into oxides during the process of extraction.
A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset, but after a futile argument, the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
Explain why, carbon cannot reduce oxides of sodium or magnesium.
Name the gas produced when calamine ore is calcined.
Which metal is extracted from cinnabar ore?
How is sodium metal extracted? Explain with the help of equation of the reaction involved.
Describe the extraction of zinc metal from its sulphide ore (zinc blende). Write equations of the reactions involved.
A sulphide ore is converted into metal oxide by the process of:
(a) carbonation
(b) roasting
(c) calcination
(d) anodising
Give the chemical formula of :
Sodium aluminate
How many valence electrons are present in non- metals?
X is an element in the form of a powder. X burns in oxygen and the product is soluble in water. The solution is tested with litmus. Write down only the word which will correctly complete each of the following sentences:
(a) If X is a metal, then the litmus will turn ______.
(b) If X is a non-metal, then the litmus will turn ______.
(c) If X is a reactive metal, then ______ will be evolved, when X reacts with dilute sulphuric acid.
(d) If X is a non -metal, it will form _ oxide, which will form ______ solution with water.
(e) If X is a non -metal, it will not conduct electricity unless it is carbon in the form of ______.
Arrange the metals of copper, iron, magnesium, sodium and zinc in the decreasing order of reactivity.
Name a non- metal that has a metallic luster and sublimes on heating.
Name the following:
The process of heating an ore to a high temperature in the presence of air.
Explain the difference between Bayer’s process and Hall’s process by explaining the Bayer’s process.
The highly reactive metals like Sodium, Potassium, Magnesium, etc. are extracted by the ____________.
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
Assertion (A): The extraction of metals from their sulphide ores cannot take place without roasting the ore.
Reason (R): Roasting converts sulphide ores directly into metals.
