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Some Basic Concepts of Chemistry

Long Answer Type

171.
Explain the following terms with examples:
1. Skeleton equation
2. Balanced equation
3. Thermochemical equation.

1. Skeleton equation. It is an equation in which reactants and products are expressed in terms of symbols and formulae but the number of atoms of various elements on both the sides of the arrow

may or may not be equal.
For example, consider the reaction of cupric oxide with ammonia to produce copper, nitrogen and water. The skeleton equation is

2. Balanced equation. It is a chemical equation representing a true chemical change in which the number of atoms of various elements on both the sides of the arrow

For example, balanced equation representing the reaction between cupric oxide and ammonia is

3. Thermochemical equation. A chemical equation which includes the heat changes taking place during the reaction is called thermochemical equation.

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Short Answer Type

172.

What do you mean by 'balancing a chemical equation'? On what principle the balancing of a chemical equation is based?

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Long Answer Type

173.

How are chemical equations balanced? discuss any two.

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174.

Balance the following equations:
$1. space space space straight H subscript 3 PO subscript 3 space space space rightwards arrow space space space space straight H subscript 3 PO subscript 4 plus PH subscript 3 2. space space space Ca plus straight H subscript 2 straight O space space rightwards arrow space space Ca left parenthesis OH right parenthesis subscript 2 plus straight H subscript 2$

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175. Translate the following equations into the language of chemistry and balance by hit and trial method:
Magnesium nitride + Water

rightwards arrow

Magnesium hydroxide + Ammonia

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176.

Balance the following skeleton equation by hit and trial method:
$Fe subscript 3 straight O subscript 4 plus straight H subscript 2 space rightwards arrow space Fe plus straight H subscript 2 straight O$

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177.

Balance the following skeleton equation by hit and trial method:
$Fe subscript 2 left parenthesis SO subscript 4 right parenthesis subscript 3 plus space NH subscript 3 plus straight H subscript 2 straight O space rightwards arrow space space space Fe left parenthesis OH right parenthesis subscript 3 plus left parenthesis NH subscript 4 right parenthesis subscript 2 SO subscript 4$

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178.

Balance the following skeleton equation:

$NH subscript 3 NI subscript 3 space rightwards arrow space space straight N subscript 2 plus straight I subscript 2 plus NH subscript 4 straight I$

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179.

Balance the following skeleton equation:

$KMnO subscript 4 plus HCl space rightwards arrow space KCl plus MnCl subscript 2 plus straight H subscript 2 straight O plus Cl subscript 2$

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180.

Balance the given skeletion equation $straight P subscript 4 plus HNO subscript 3 space rightwards arrow space space straight H subscript 3 PO subscript 4 plus NO subscript 2 plus straight H subscript 2 straight O$ by partial equation method.