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प्रश्न
Write chemical equation for the event.
Electrolysis of alumina is done.
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)
संबंधित प्रश्न
Give one example each of which illustrates the following characteristics of a chemical reaction:
evolution of a gas
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Also give balanced equations for the reactions
What do you observe when Magnesium ribbon is burnt in oxygen.
What is meant by the metal reactivity series ? State its importance, (any two points).
Write the chemical equation for the event.
A reaction was brought about between ferric oxide and aluminum.
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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.
Complete the statement by filling in the blank with the correct word:
The metal which reacts with steam and the reaction is reversible is ________.
In preparation of Aqua regia hydrochloric acid and _______ acid are mixed.
Classify the following metals based on their reactivity.
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| More reactive | Moderately reactive | Less reactive |
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A metal that exists as a liquid at room temperature is obtained by heating its sulphide in the presence of air. Identify the metal and its ore and give the reaction involved.
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.
Metal ‘A’ has electronic configuration 2, 8, 1 and metal ‘B’ has electronic configuration 2, 8, 8, 2. Out of these, which metal is more reactive? Write the reaction of this metal with dilute HCl acid.
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?
