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प्रश्न
Explain the following reaction with the balanced equation.
Dry aluminium hydroxide is ignited at 1000 °C
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उत्तर
When dry aluminium hydroxide is calcined by at 1000 °C, pure aluminium oxide, called alumina is obtained.
\[\ce{\underset{\text{Aluminium hydroxide}}{2Al(OH)_{3(s)}} ->[heat][1000 °C] \underset{\text{Aluminium oxide}}{Al2O_{3(s)}} + \underset{\text{Water vapour}}{3H2O_{(g)}}}\]
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संबंधित प्रश्न
Name two metals which are found in nature in the free state.
Give reasons.
Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
Explain giving one example, how highly reactive metals (which are high up in the reactivity series) are extracted.
Describe with one example, how moderately reactive metals (which are in the middle of reactivity series) are extracted.
Define the term ore.
Name the gas produced when calamine ore is calcined.
Name the electrode at which aluminium metal is produced.
An important ore of zinc metal is:
(a) calamine
(b) cuprite
(c) pyrolusite
(d) haematite
Rock salt is an ore of one of the following metals. This metal is:
(a) Mn
(b) Na
(c) Fe
(d) Cu
The metal which can be extracted from pyrolusite ore is:
(a) mercury
(b) manganese
(c) aluminium
(d) magnesium
State three objectives achieved during the roasting of ores.
Give reasons, why aluminum is used in:
painting electric and telegraphic poles
Aluminum is used in thermite welding:
write reaction for process?
Answer the following questions based on the extraction of aluminium from alumina by Hall - Heroult’s Process :
What is the function of cryolite used along with alumina as the electrolyte?
Define the term:
Flux
Which one of the following is not true of metal :
Metals are good conductors of electricity.
Which one of the following is not true of metal :
Metals are malleable and ductile
Gold and silver are active metals.
An alloy is
On the basis of reactivity metals are grouped into three categories:
- Metals of low reactivity
- Metals of medium reactivity
- Metals of high reactivity
Therefore metals are extracted in pure form from their ores on the basis of their chemical properties.
Metals of high reactivity are extracted from their ores by electrolysis of the molten ore.
Metals of low reactivity are extracted from their sulphide ores, which are converted into their oxides. The oxides of these metals are reduced to metals by simple heating.
(a) Name the process of reduction used for a metal that gives vigorous reaction with air and water both.
(b) Carbon cannot be used as a reducing agent to obtain aluminium from its oxide? Why?
(c) Describe briefly the method to obtain mercury from cinnabar. Write the chemical equation for the reactions involved in the process.
OR
(c) Differentiate between roasting and calcination giving chemical equation for each.
