How is ore purified (give equations also) - Vidyadip

Question

How is ore purified (give equations also)

✓

Answer

Purification of aluminium ore is done by the Baeyers process.
Baeyers process involves the following steps:
1. Bauxite is crushed to a fine powder.
2. The powdered bauxite is then treated with a strong solution of sodium hydroxide.
3. The mixture is then heated under pressure to $150^{\circ} C$ to $250^{\circ} C$ for about 30 minutes. The heat and the pressure cause the alumina to dissolve in the sodium hydroxide to form sodium aluminate.
$
Al _2 O _3 \cdot 2 H _2 O +2 NaOH \longrightarrow 2 NaAlO _2+3 H _2 O
$
Alumina being amphoteric dissolves in sodium hydroxide.
4. The sodium aluminate solution is then filtered to separate the impurities.
5. The solution of sodium aluminate is then cooled lightly and sent into tanks called precipitators.
6. Crystals of aluminium hydroxide are then added when most of the sodium aluminate undergoes hydrolysis to precipitate insoluble aluminium hydroxide.
$
NaAIO _2+2 H _2 O \longrightarrow NaOH + Al ( OH )_3
$
7. The solid aluminium hydroxide is separated by filtration.
8. The solid aluminium hydroxide is then washed and again filtered and dried, and then heated to about $1100^{\circ} C$ to $1200^{\circ} C$, when aluminium hydroxide decomposes to form aluminium oxide.
$
2 Al ( OH )_3 \longrightarrow Al _2 O _3+3 H _2 O
$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "[5 Mark Question Answer]" from Metallurgy→Metallurgy — all question types→Chemistry STD 10 question papers→ICSE Board STD 10 question papers→ICSE Board question paper generator→

Similar questions

Making use only of substances chosen from those given below:
Dilute sulphuric acid
Sodium carbonate
Zinc
Sodium sulphite
Lead
Salcium carbonate
Give the equation for the reaction by which you could obtain:
(i) Hydrogen
(ii) Sulphur dioxide
(iii) Carbon dioxide
(iv) Zinc Carbonate (two steps required).

You are given three white powders-calcium carbonate, lead carbonate and zinc carbonate. Describe the tests you would carry out in solution, to identify the metal ion in each of the above compounds. Indicate clearly how you would prepare the solutions for the tests.

Compare the process of calcination and roasting.

The volume of gases $A, B, C$, and $D$ are in the ratio, $1: 2: 2: 4$ under the same conditions of temperature and pressure.
(i) Which sample of gas contains the maximum number of molecules?
(ii) If the temperature and pressure of gas A are kept constant, then what will happen to the volume of $A$ when the number of molecules is doubled?
(iii)If this ratio of gas volume refers to the reactants and products of a reaction, which gas law is being observed?
(iv)If the volume of A is actually $5.6 dm ^3$ at S.T.P., calculate the number of molecules in the actual Volume of D at S.T.P. (Avogadro's number is $6 \times 10^{23}$ ).
(v) Using your answer from (iv), state the mass of $D$ if the gas is dinitrogen oxide $\left( N _2 O \right)$

State your observations when ammonium hydroxide solution is added drop by drop and then in excess to each of the following solutions :
1) Copper sulphate solution
2) Zinc sulfate solution.

A gas cylinder can hold $1\ \ kg$ of hydrogen at room temperature and pressure.
$(a)$ Find the number of moles of hydrogen present
$(b)$ What weight of $CO_2$ can the cylinder hold under similar conditions of temperature and pressure? $(H = 1 C = 12, O = 16)$
$(c)$ If the number of molecules of hydrogen in the cylinder is $X,$ calculate the number of $CO_2$ molecules in the cylinder with the same conditions of temperature and pressure.
$(d)$ State the law that helped you to arrive at the above result.

The percentage composition of sodium phosphate, as determined by analysis is $: 42.1\% \ Na, 18.9\%\ P, 39\%$ of $O$. Find the empirical formula of the compound.
$[H =1, N =14, Na = 23, P = 31, Cl = 35.5, Pt = 195]$

How an ore is concentrated by froth floatation process?

The pH values of three solutions P, Q and R are given in the table.

Solution	pH value
P	12
Q	2
R	7

Answer the following questions :
(i) Which solution will have no effect on litmus solution?
(ii) Which solution will liberate CO₂ when reacted with sodium carbonate?
(iii) Which solution will turn red litmus blue?
(iv) Which solution will turn blue litmus red?
(v) Which solution is also known as alkali?

Propane burns in air according to the following equation :
$C_3H_{8 }+ 5O_{2 }\rightarrow 3CO_2 + 4H_2O$
What volume of propane is consumed on using $1000 \ cm^3$ of air, considering only $20\%$ of air contains oxygen?