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प्रश्न
| A process of forming a thick oxide of aluminium when aluminium is exposed to air. This coat makes it resistant to corrosion. Resistance can be improved by making a layer of oxide thinker. In this technique, the aluminium article is the anode, and the electrolyte is sulphuric acid. The anode reaction results in the formation of a black-coloured film of aluminium oxide on the anode. By putting appropriate dyes in the electrolytic solution, both coloured surface with the decorative finish is achieved. Kitchen articles like anodised such as pressure cookers, pans and frames of sliding windows are applications of this technique. |
- Name the anode and electrolyte used in this technique.
- How can we make aluminium articles made resistant to corrosion?
- Name the technique used to coat the aluminium articles.
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उत्तर
- In this process, the anode is an aluminium object to be coated, and the electrolyte is diluted sulfuric acid.
- When aluminium oxide is applied to an object made of aluminium, corrosion resistance is increased.
- The technique is known as 'Anodising'.
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संबंधित प्रश्न
Write two methods of preventing the rusting of iron.
Why do we apply paint on iron articles?
Answer the following question.
What are alloys?
Give reasons:
Platinum, gold and silver are used to make jewellery.
Choose the correct answer from the options given below:
Heating an ore in a limited supply of air or in the absence of air at a temperature just below its melting point is known as
A. Smelting
B. Ore-dressing
C. Calcination
D. Bessemerisation
The chemical reaction involved in the corrosion of iron metal is that of:
(a) oxidation as well as displacement
(b) reduction as well as combination
(c) oxidation as well as combination
(d) reduction as well as displacement
Explain why, iron sheets are coated with zinc.
In one method of rust prevention, the iron is not coated with anything. Which is this method?
Fill in the following blank with suitable word:
The corrosion of iron is called ................
Fill in the following blank with suitable word:
The process of depositing a thin layer of zinc on iron articles is called .............
Name two metals which resist corrosion due to the formation of a thin, hard and impervious layer of oxide on their surface.
Explain why, the galvanised iron article is protected against rusting even if the zinc layer is broken.
A common metal which is highly resistant to corrosion is:
(a) iron
(b) copper
(c) aluminium
(d) magnesium
A metal X which is resistant to corrosion is produced by the electrolysis of its molten oxide whereas another metal Y which is also resistant to corrosion is produced by the reduction of its oxide with carbon. Metal X can be used in powder form in thermite welding whereas metal Y is used in making cathodes of ordinary dry cells.
(a) Name the metals X and Y.
(b) Which of the two metals is more reactive : X or Y?
(c) Name one ore or metal X. Also write its chemical formula.
(d) Name one ore or metal Y. Also write its chemical formula.
(e) Name one alloy of metal X and one alloy of metal Y.
Explain with reason:
Roasting is carried out on sulphide ores and not on carbonate ores.
What are the adverse effects of corrosion?
Write three methods of preventing rusting of iron.
Give reason.
An iron article should be given a coat of paint
Observe the following picture and answer the following questions:
- What is rust?
- Write the chemical formula of rust.
- Write the reaction of oxidation of iron at the anode.
- Write the reaction of oxidation of iron at the cathode.
- What is corrosion?
_______ forms a green colour in the water.
Rusting of iron : Fe2O3 : : corrosion of copper : ______
Bronze : _______ : : Stainless steel : Fe + Cr + C
Find the odd one out and give its explanation.
Explain concept with example/explain with the help of a balanced equation.
Corrosion
What is rust?
Galvanisation is a method of protecting iron from rusting by coating it with a thin layer of ____________.
Copper objects lose their shine and form green coating of ____________.
Which among the following alloys contain mercury as one of its constituents?
Marble’s popularity began in ancient Rome and Greece, where white and off-white marble were used to construct a variety of structures, from hand-held sculptures to massive pillars and buildings.
The substance not likely to contain CaCO3 is:
Iron pillar near the Qutub Minar in Delhi is famous for the following facts. Which of these facts is responsible for its long stability?
Explain the following:
Bubbles are produced when acetic acid is added to a solution of sodium hydrogencarbonate.
Give an example of a chemical reaction for the following situation:
Sound is produced
Give scientific reasons.
Silver amalgam is used for filling dental cavities.
Describe two changes that are harmful. Explain why you consider them harmful. How can you prevent them?
