Class 10 Science Complete Notes (Grade A)

Summary:

This Class 10 Science Complete Notes provide information on chemical reactions and equations. It begins by explaining that a chemical reaction occurs when a chemical change occurs, such as food digestion or rusting of iron. Chemical reactions can be represented symbolically using chemical equations. For example, the burning of magnesium in the air to form magnesium oxide can be represented as Mg + O2 → MgO.

The note highlights that chemical reactions can be recognized by observing changes in state, colour, gas evolution, or temperature. Physical states of reactants and products are often indicated, such as (g) for gas, (l) for liquid, (s) for solid, and (aq) for aqueous solutions. Chemical equations need to be balanced to ensure that the number of atoms of each element remains the same on both sides of the equation.

Various types of chemical reactions are discussed, such as combination reactions, where two or more substances combine to form a new substance. For example, calcium oxide and water combine to form calcium hydroxide. Other types of reactions covered include decomposition reactions, displacement reactions, double displacement reactions, and precipitation reactions.

The note also introduces concepts like exothermic and endothermic reactions, oxidation, reduction, and redox reactions. It explains corrosion and rancidity as examples of chemical changes that occur in everyday life. The use of antioxidants in food to prevent rancidity is mentioned as well.

Excerpt:

Class 10 Science Complete Notes

CHAPTER – 1
Chemical Reaction: – Whenever a chemical change occurs, we can say that a chemical reaction has taken place
e.g.:

• Food gets digested in our body
• Rusting of iron.

Chemical Equation:– A chemical reaction can be expressed symbolically by using the chemical equation magnesium is burnt into the air to form magnesium oxide can be represented as:

Mg + O2 → MgO

We can observe or recognise a chemical reaction by observing changes in state, colour, by the evolution of gas or by a change in temperature.

The physical state of the reactant and products are mentioned to make the chemical reaction more informative. e.g. we use (g) for gas, (l) for liquid, (s) for solid and (aq) for aqueous.