Class 10 Science Chapter 1 Notes
Chemical Reactions and Equations
Here we are providing notes of the first chapter of Class 10 Science “Chemical Reactions and Equations”. In this chapter, the main features related to Chemical Reactions and Equations have been studied.
These notes will prove useful for those students who are preparing for the board exam this year. This material prepared in simple and systematic language will help in revising the chapter quickly and remembering the main points.
chemical reaction
- Chemical Reaction: The process of interaction of chemical substance to form new chemical substance is known as Chemical Reaction. For example: Rusting of iron, the setting of milk into curd, digestion of food, respiration, etc.
- In a chemical reaction, a new substance is formed which is completely different in properties from the original substance, so in every chemical reaction, there is always a chemical change takes place.
- Only a rearrangement of atoms takes place in a chemical reaction.
- The substances which take part in a chemical reaction are called reactants.
- The new substances produced as a result of a chemical reaction are called products.
Example: The burning of magnesium in the air to form magnesium oxide is an example of a chemical
reaction.
Before burning in air, the magnesium ribbon is cleaned by rubbing with sandpaper.
This is done to remove the protective layer of basic magnesium carbonate from the surface of the
magnesium ribbon.
Reactant
- Substances which take part in a chemical reaction are called reactants.
- Example: Mg and O2.
Product
- New substance formed after a chemical reaction is called a product.
- Example: MgO.
Characteristics of Chemical Reactions
(i) Evolution of gas: The chemical reaction between zinc and dilute sulphuric acid is characterised by the
evolution of hydrogen gas.
(ii) Change in Colour: The chemical reaction between citric acid and purple coloured potassium
permanganate solution is characterised by a change in colour from purple to colourless.
The chemical reaction between sulphur dioxide gas and acidified potassium dichromate solution is
characterized by a change in colour from orange to green.
(iii) Change in state of substance: The combustion reaction of candle wax is characterised by a change in state from solid to liquid and gas (because the wax is a solid, water formed by the combustion of wax is a liquid at room temperature whereas, carbon dioxide produced by the combustion of wax is a gas). There are some chemical reactions which can show more than one characteristics.
(iv) Change in temperature: The chemical reaction between quick lime water to form slaked lime is
characterized by a change in temperature (which is a rise in temperature).
The chemical reaction between zinc granules and dilute sulphuric acid is also characterised by a change in temperature (which is a rise in temperature).
(v) Formation of precipitate: The chemical reaction between sulphuric acid and barium chloride solution is characterised by the formation of a white precipitate of barium sulphate.
Chemical Equation
Those final goods and services which directly satisfy the human wants of the consumer. The goods and services purchased by the consumer are consumer goods.
capital goods
These are the final goods that help in production and are used for income generation. These increase the capital assets of the producer and are durable in nature.
Final goods
Final goods are those goods which have crossed the production line and are ready for use by their final users. That is, those which are used for consumption or investment.
Consumers
The persons/entities who consume final goods and services to satisfy their wants are called consumers.
Producers
The firms/organisations that produce final goods and services are called producers.
intermediate goods
These are goods and services which can be resold in the same year or are used as raw material in the production of final goods or which can be transformed. These do not directly fulfill human needs. Services used by the producer such as lawyer’s services; raw materials etc. are intermediate goods.
depreciation
The decrease in the value of fixed assets due to normal wear and tear, obsolescence and passage of time is called depreciation or consumption of fixed capital. Depreciation is calculated by dividing the value of fixed capital by its estimated life (in years).
Investment
The increase in the stock of capital goods in a given period is called investment. It is also called capital formation or investment.
Gross Investment:
The total increase in the stock of capital goods in a given time period is called gross investment. It includes depreciation. It is also called gross capital formation.
Net Investment:
Net investment is the net increase in the stock of capital goods in an economy over a period of time. It does not include depreciation.
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