important notes of the language of chemistry class 7
Answers
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Explanation:
A chemical reaction involves the transformation of original substance into an altogether new substance(s).
A chemical reaction can be represented with the help of the symbols or the formulae of the elements and the compounds taking part in that reaction. This gives a chemical equation.
Certain necessary conditions for a chemical reaction to happen are close contact, solution form, heat, light and catalyst.
Characteristics of chemical reactions are change of colour, evolution of a gas, formation of a precipitate, change of state, change of smell and evolution/absorption of heat.
A complete chemical equation symbolically represents the reactants, products and their physical states.
The substances that react with each other are called reactants and they are represented on the left hand side of the equation. The substances that are formed as a result of the reaction are called products. They are represented on the right hand side of the equation.
A chemical equation needs to be balanced to make it follow the law of the conservation of mass.
The law of conservation of mass states that mass can be neither created nor destroyed, it can only be transformed from one form to another.
A chemical equation gives both qualitative and quantitative information about the reactants and products.