Chemistry:

The theoretical and experimental study of nature, composition, preparation, isolation, properties and uses of matter is known as Chemistry.

Chemical Reaction:  Such a process in which there produces substances of new property is known as chemical reaction.  Ex.

2H₂ + O₂ → 2H₂O

(Here H₂ and O₂ take part in chemical reaction and produce a product of new property i.e. H₂O.)

In other hand, we can also say that Chemical changes are also known as chemical reaction. There are many chemical changes which occur around us.

Like,

• Iron rod comes in contact of moisture and gets rusted.
• Grapes get fermented.
• Food is cooked.
• Food gets digested in our body.
• We respire.

Determination of Chemical Reaction:

We should have a criteria to determine the chemical reaction has taken place.

e.i

• change in state
• change in colour
• evolution of a gas
• Change in temperature.

 

Above four points are identifications of chemical reaction which indicate that the reaction has taken place.

 

Chemical Equation

when a magnesium ribbon is burnt in oxygen, it gets converted to magnesium oxide. This is the statement form of a chemical reaction but it can be write as a following manners

Magnesium + Oxygen → magnesium oxide

        (Reactants)                      (product)

To write the equation in such manner is called as word equation.

Another method to write chemical reaction;

Mg + O₂ → MgO

This is symbolic form to write chemical equations. 

There are two part of a chemical reaction

1. Reactants: The substances that undergo chemical change in the reaction  are the reactants. Example from above equation. Mg and O are reactants.
2. Procducts: The new substance,  formed during the reaction, is the product. Ex. MgO is product, which newer substance produced in reaction.