Advertisements
Advertisements
प्रश्न
Write chemical equation for the event.
Electrolysis of alumina is done.
Advertisements
उत्तर १
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
उत्तर २
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
संबंधित प्रश्न
What do you observe when dilute sulphuric acid is added to granulated zinc?
How will you obtain Silver chloride from silver nitrate.
Also give balanced equations for the reactions
What do you observe when magnesium ribbon is burnt in oxygen?
Write a chemical equation for the following event.
Zinc oxide is dissolved in dilute hydrochloric acid.
With reference to Water explain with suitable examples of how the reactivity of the metals could be differentiated.
Give a balanced equation for the reversible catalytic reaction involving nitrogen as one of the reactants.
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.
In preparation of Aqua regia hydrochloric acid and _______ acid are mixed.
Explain the following reaction with the balanced equation.
Magnesium reacts with dil HCl
Explain the following reaction with the balanced equation.
Sulphur burns in air
Which of the following is the correct arrangement of the given metals in ascending order of their reactivity?
Zinc, Iron, Magnesium, Sodium
Which among the following statements is incorrect for magnesium metal?
A metal A, which is used in thermite process, when heated with oxygen gives an oxide B, which is amphoteric in nature. Identify A and B. Write down the reactions of oxide B with HCl and NaOH.
An element A reacts with water to form a compound B which is used in white washing. The compound B on heating forms an oxide C which on treatment with water gives back B. Identify A, B and C and give the reactions involved.
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.
Three metal samples of magnesium, aluminium and iron were taken and rubbed with sandpaper. These samples were then put separately in test tubes containing dilute hydrochloric acid. Thermometers were also suspended in each test tube so that their bulbs dipped in the acid. The rate of formation of bubbles was observed. The above activity was repeated with dilute nitric acid and the observations were recorded.
Answer the following questions:
(i) When the activity was done with dilute hydrochloric acid, then in which one of the test tubes was the rate of formation of bubbles the fastest and the thermometer showed the highest temperature?
(ii) Which metal did not react with dilute hydrochloric acid? Give reason.
(iii) Why is hydrogen gas not evolved when a metal reacts with dilute nitric acid? Name the ultimate products formed in the reaction.
OR
Name the type of reaction on the basis of which the reactivity of metals is decided. You have two metals X and Y. How would you decide which is more reactive than the other?
