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प्रश्न
Explain concept with example/explain with the help of a balanced equation.
Corrosion
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उत्तर
- The process of slow degradation of the metals due to the attack of atmospheric gases, moisture, acids, etc. on the surface of metals is called corrosion.
- Iron reacts with moist air and a deposit of reddish substance (Fe2O3.H2O) is formed on it. This substance is called rust and the corrosion of iron is known as rusting.
- Carbon dioxide in moist air reacts with the surface of copper vessel. Copper loses its lustre due to formation of a greenish layer of copper carbonate (CuCO3) on its surface. This is called patination of copper.
- Various methods such as galvanizing, tinning, alloying, etc. are used to protect metals from corrosion.
APPEARS IN
संबंधित प्रश्न
Tinning : Tin : : Galvanizing : _________
Give reasons:
Platinum, gold and silver are used to make jewellery.
Explain why Iron sheets are coated with zinc during galvanization.
What type of chemical reaction is involved in the corrosion of iron?
Name any three objects (or structures) which are gradually damaged by the corrosion of iron and steel.
The chemical reaction involved in the corrosion of iron metal is that of ______.
State two conditions for the rusting of iron.
In one method of rust prevention, the iron is not coated with anything. Which is this method?
Explain why, though aluminium is more reactive than iron, yet there is less corrosion of aluminium when both are exposed to air.
Give the constituents of brass.
Name five methods of preventing rusting of iron.
What are the special properties of stainless steel?
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.
- Name the metals X and Y.
- Which of the two metals is more reactive: X or Y?
- Name one ore or metal X. Also write its chemical formula.
- Name one ore of metal Y. Also write its chemical formula.
- Name one alloy of metal X and one alloy of metal Y.
Four metals P, Q, R and S are all obtained by the reduction of their oxides with carbon. Metal P is used to form a thin layer over the sheets of metal S to prevent its corrosion. Metal Q is used for electroplating tiffin boxes made of metal S whereas metal R is used in making car batteries. Metals Q and R form an alloy called solder. What are metals P, Q, R and S? How have you arrived at this conclusion?
Mention two uses of the following metals and non-metals
Iron
Name the metal which is a constituent of plant pigment?
State under what conditions corrosion is faster ?
No chemical reaction takes place when granules of a solid, A, are mixed with the powder of another solid, B. However when the mixture is heated, a reaction takes place between its components. One of the products, C, is a metal and settles down in the molten state while the other product, D, floats over it. It was observed that the reaction is highly exothermic.
(i) Based on the given information make an assumption about A and B and write a chemical equation for the chemical reaction indicating the conditions of reaction, physical state of reactants and products and thermal status of reaction.
(ii) Mention any two types of reactions under which above chemical reaction can be classified.
Write scientific reasons.
Lemon or tamarind is used for cleaning copper vessels turned greenish.
Complete the process of iron rusting by filling the blanks. Suggest a way to prohibit the process.
The iron rust is formed due to........................... reaction. Different
regions on iron surface become anode and cathode.
Reaction on anode region :
`F_e(s) → Fe^(2+) (aq) +2e^-`
Reaction on anode region :
`O_2(g) + 4H^+(aq) +............................ → 2H_2 O (l) `
When Fe2+ ions migrate from anode region they react with ................... to form Fe3+ ions.
A reddish coloured hydrated oxide is formed from ............... ions. It is called rust.
`2Fe_(3+) (aq) + 4H_2O(l) → ................. + 6H_+(aq) `
A way to prevent rusting ..................................................................
Identify the process shown in the diagram and explain it in short
What is done to prevent corrosion of metals?
Write three methods of preventing rusting of iron.
Give reason.
An iron article should be given a coat of paint
Give reason.
Copper and brass utensils should be tinned.
When one of the metals in an alloy is mercury the alloy is called _______.
Write the name.
An alloy of copper and tin-
Write scientific reason.
Coins are made from metals and alloys.
Draw a neat labelled diagram.
Anodizing
Observe the following diagram and write answers.
- Name the method.
- Explain the method.
- Give two examples of this method.
Observe the following figure and write the answer of the question.
- Which process is shown in the figure?
- Explain the chemical reaction shown in the figure.
- Write the reactions on anode and cathode.
What is rust?
Give the equation for the formation of rust.
Galvanisation is a method of protecting iron from rusting by coating it with a thin layer of ____________.
Identify the correct statement from the following:
Alloys are homogeneous mixtures of a metal with a metal or non-metal. Which among the following alloys contain non-metal as one of its constituents?
Galvanisation is a process used to prevent the rusting of which of the following?
Explain the following:
Lime water turns milky on passing carbon dioxide gas into it.
Give an example of a chemical reaction for the following situation:
Sound is produced
