Question

Define chemical equation with four examples Class- 7

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Answer 1

Answer:

A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and formulae, wherein the reactant entities are given on the left-hand side and the product entities on the right-hand side.

Explanation:

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Answer 2

Answer:

The different types of chemical reaction are:

1. Combination reaction

2. Decomposition reaction

3. Displacement reaction

4. Neutralisation reaction

5. Double displacement reaction

6. Oxidation and reduction reaction

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1. Combination reaction:

In a combination reaction, two or more elements combine to form a compound or an element and a compound can combine to form a new compound

For example:

Magnesium and oxygen combine when heated to form magnesium oxide.

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: Combination\: \\ 2Mg(s)+O2(g) \: \: \: \: \: \: \: \: \: \: \: \: \: \: \longrightarrow\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: 2MgO(s)$

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2. Displacement reaction:

Those reactions in which one element takes the place of another element in a compound, are known as displacement reaction. In general a more reactive element displacement reaction. In general, a more reactive element displaces a less reactive element from its compound.

For example:

When a strip zinc metal is placed in a copper sulphate solution, then zinc sulphate solution and copper are obtained:

$CuSO4(aq)+Zn(s)→ZnSO4(aq)+Cu(s)$

In this reaction zinc displaces copper from copper sulphate solution.

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3. Double displacement reaction:

Those reactions in which two compounds by the exchange of ions to form two new compound are called double displacement reactions. A double displacement reaction usually occurs in solution and one of the products, being insoluble, precipitates out.

For example:

When silver nitrate solution is added to sodium chloride solution, then a white precipitate of silver chloride is formed long with sodium nitrate solution :

$</p><p>AgNO2(aq)+NaCl(aq)→AgCl(s)+NaNO3.</p><p></p><p>$

In this double displacement reaction, two compounds, silver nitrate and sodium nitrate.

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4. Oxidation and reduction reactions:

Oxidation:

1. The addition of oxygen to a substance is called oxidation.

2. The removal of hydrogen from a substance is also called oxidation.

Reduction:

1. The addition of hydrogen to a substance is called reaction.

2. The removal of oxygen from a substance is also called reduction.

From the above definitions, it is clear that the process of reduction is just opposite oxidation. Moreover, oxidation and reduction reactions occur together.