Advertisements
Advertisements
Question
Write chemical equation for the event.
Electrolysis of alumina is done.
Advertisements
Solution 1
The electrolysis of alumina is carried out in a steel tank lined inside with graphite. The graphite lining serves as cathode. Anode is also made up of graphite rods hanging in the molten mass. The electrolyte consists of alumina dissolved in fused Cryolite(Na3AlF6) and Fluorspar(CaF2). Cryolite lowers the melting point of alumina and fluorspar increases the fluidity of the mass so that the liberated aluminum metal may sink at the bottom of the cell. When electric current is passed through this mixture, the aluminum is collected at the cathode in molten state and sinks at the bottom.
Ionization of Alumina:2Al2O3 → 6O-2 + 4Al+3
Reaction at Cathode: 4Al+3 + 12e- → 4Al
Reaction at Anode: 6O-2 → 3O2 + 12e-, C + O2 → CO2
Solution 2
When electrolysis of alumina is done, aluminium is formed at the cathode and oxygen gas liberated at the anode.
Cathode:
\[\ce{Al^{3+} + 3e^- -> Al_{(l)}}\] (Reduction)
Anode:
\[\ce{2O^2- -> O_{2(g)} + 4e^-}\] (Oxidation)
APPEARS IN
RELATED QUESTIONS
What do you observe when a few pieces of iron are dropped in a blue solution of copper sulphate?
What do you observe when ferrous sulphate solution is added to an aqueous solution of sodium hydroxide.
Fill in the blank
When a piece of copper is added to silver nitrate solution, it turns ............in colour.
How will you obtain Magnesium oxide from magnesium.
Also give balanced equations for the reactions
How will you obtain Zinc chloride from zinc.
Also give balanced equations for the reactions
What is meant by the metal reactivity series ? State its importance, (any two points).
Write a chemical equation for the event.
Iron filings are dropped in aqueous solution of copper sulphate.
Write the chemical equation for the event.
A reaction was brought about between ferric oxide and aluminium.
State what is meant by the ‘reactivity series of metals’
With reference to Water explain with suitable examples of how the reactivity of the metals could be differentiated.
Select the correct answer for the statement given below:
A neutral oxide which does not react with an acid or a base to give salt and water.
Classify the following metals based on their reactivity.
Cu, Zn, Ca, Mg, Fe, Na, Li, Hg
| More reactive | Moderately reactive | Less reactive |
Explain the following reaction with the balanced equation.
Magnesium reacts with dil HCl
A metal M does not liberate hydrogen from acids but reacts with oxygen to give a black colour product. Identify M and black coloured product and also explain the reaction of M with oxygen.
A solution of CuSO4 was kept in an iron pot. After few days the iron pot was found to have a number of holes in it. Explain the reason in terms of reactivity. Write the equation of the reaction involved.
Explain the following
- Reactivity of Al decreases if it is dipped in HNO3
- Carbon cannot reduce the oxides of Na or Mg
- NaCl is not a conductor of electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state
- Iron articles are galvanised.
- Metals like Na, K, Ca and Mg are never found in their free state in nature.
Of the three metals X, Y and Z. X reacts with cold water, Y with hot water and Z with steam only. Identify X, Y and Z and also arrange them in order of increasing reactivity.
An element A burns with golden flame in air. It reacts with another element B, atomic number 17 to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also write down the equations for the reactions involved.
