Advertisements
Advertisements
Question
In the extraction of aluminium by Hall-Heroult process, purified \[\ce{Al2O3}\] is mixed with \[\ce{CaF2}\] to:
(i) lower the melting point of \[\ce{Al2O3}\].
(ii) increase the conductivity of molten mixture.
(iii) reduce \[\ce{Al^{3+}}\] into \[\ce{Al(s)}\].
(iv) acts as catalyst.
Advertisements
Solution
(i) lower the melting point of \[\ce{Al2O3}\].
(ii) increase the conductivity of molten mixture.
Explanation:
\[\ce{CaF2}\] mixed with purified \[\ce{Al2O3}\] helps in lowering the melting point of \[\ce{Al2O3}\] and increases the conductivity of the molten mixture.
APPEARS IN
RELATED QUESTIONS
Write the names and chemical formulae of any one ore of iron.
What is the chemical composition of malachite?
- CuO . CuC03
- Cu(OH)2 CuC03
- CuO.Cu(OH)2
- Cu2O . Cu(OH)2
Silica is added to roasted copper ore during smelting process to remove _______.
(A) ferrous sulphide
(B) ferrous oxide
(C) cuprous sulphide
(D) cuprous oxide
What is the role of cryolite in the extraction of aluminium?
In the extraction of Al, impure Al2O3 is dissolved in conc. NaOH to form sodium aluminate and leaving impurities behind. What is the name of this process?
Differentiate between “minerals” and “ores”.
Which among the following minerals does NOT contain aluminium?
(a) Cryolite
(b) Siderite
(c) China clay
(d) Corundum
Describe the role of the cryolite in the extraction of aluminium from pure alumina.
How will you convert the following:
[Ag(CN)2]− to Ag
Metal which is found in free state is:
Which among the following statement is correct?
When copper ore is mixed with silica, in a reverberatory furnace copper matte is produced. The copper matte contains ______.
The main reactions occurring in blast furnace during extraction of iron from haematite are:
(i) \[\ce{Fe2O3 + 3CO -> 2Fe + 3CO2}\]
(ii) \[\ce{FeO + SiO2 -> FeSiO3}\]
(iii) \[\ce{Fe2O3 + 3C -> 2Fe + 3CO}\]
(iv) \[\ce{CaO + SiO2 -> CaSiO3}\]
The important ore of iron is:-
In the thermite process, the reducing agent is:
In the extraction of iron, the slag produce is
Match List - I with List - II.
| List - I | List - II | ||
| (One) | (Composition) | ||
| (A) | Siderite | (I) | FeCO3 |
| (B) | Malachite | (II) | CuCO3 · Cu(OH)2 |
| (C) | Sphalerite | (III) | ZnS |
| (D) | Calamine | (IV) | ZnCO3 |
Choose the correct answer from the options given below:
Calamine and Malachite, respectively, are the ores of ______.
The ore that contains both iron and copper is ______.
