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प्रश्न
Write a short note on Alloying.
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उत्तर
- The homogenous mixture formed by mixing metal with other metals or nonmetals in a certain proportion is called an alloy.
- Majority of the metallic substances used presently are in the form of alloys. The main intention behind this is to decrease the intensity of corrosion of metals.
- For example, bronze is an alloy formed from 90% copper and 10% tin. Bronze statues do not get affected by the sun and rain. Stainless steel does not get stains with air or water and also does not rust. It is an alloy made from 74% iron, 18% chromium and 8% carbon.
- In recent times various types of alloys are used for minting coins.
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संबंधित प्रश्न
Give two examples of alloys with their chemical composition.
Give reasons:
Platinum, gold and silver are used to make jewellery.
Explain how painting of an iron gate prevents it from rusting.
What type of chemical reaction is involved in the corrosion of iron?
In one method of rust prevention, the iron is not coated with anything. Which is this method?
Fill in the following blanks with suitable words:
Tiffin boxes are electroplated with .............. but car bumpers are electroplated with ............... to protect them from rusting.
Fill in the following blanks with suitable words:
............ and .............. are necessary for the rusting of iron.
What is meant by 'rusting of iron'? With the help of labelled diagrams, describe an activity to find out the conditions under which iron rusts.
In stainless steel alloy, iron metal is mixed with:
(a) Cu and Cr
(b) Cr and Ni
(c) Cr and Sn
(d) Cu and Ni
Brass is an alloy of:
(a) Cu and Sn
(b) Cu and Pb
(c) Pb and Sn
(d) Zn and Cu
Name the metal which is a constituent of blood pigment?
What is corrosion? What are necessary conditions for corrosion?
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.
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.
A wooden article should be polished.
Give reason.
Copper and brass utensils should be tinned.
Explain the term – rusting and give a word equation for the formation of rust. If polished iron nails are kept in three separate test tubes, state the contents in each test tube required, to prove the conditions for rusting.
Give reason for the following:
A suspension of rust is basic in nature.
Corrosion of silver causes a black layer of _______.
_______ forms a green colour in the water.
Stainless steel is an alloy of _______.
Write the name.
An alloy of copper and tin-
Write a molecular formula for rust.
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.
The process of coating the surface of the metal with a thin layer of zinc is called ______
Galvanisation is a method of protecting iron from rusting by coating it with a thin layer of ____________.
The diagram shows the reaction between metal and dil. acid.
What is the reason for different behaviour of Mg in test tube B?
The table shown below gives information about four substances: A, B, C and D.
| SUBSTANCE | MELTING POINT (K) | ELECTRICAL CONDUCTIVITY | |
| SOLID | LIQUID/ AQUEOUS | ||
| A | 295 | Good | Good |
| B | 1210 | Poor | Good |
| C | 1890 | Poor | Good |
| D | 1160 | Poor | Poor |
Identify Ionic compounds from the above given substances.
Identify the correct statement from the following:
Generally, when metals are treated with mineral acids, hydrogen gas is liberated but when metals (except Mn and Mg), treated with HNO3, hydrogen is not liberated, why?
Galvanisation is a process used to prevent the rusting of which of the following?
In ______ process a layer of molten tin is deposited on metals.
