Is it chemical change or physical change? give reasons. a a glass bottle breaking b butter and sugar being made into toffee c cotton being woven to make sheets d coal burning in air
The Correct Answer and Explanation is:
Here are the explanations for each case:
a) A glass bottle breaking: Physical Change
- Reason: When a glass bottle breaks, it undergoes a change in its shape and size, but its chemical composition remains the same. The breaking is simply a physical alteration, not a chemical reaction. No new substances are formed, and no bonds are broken or created at the molecular level.
b) Butter and sugar being made into toffee: Chemical Change
- Reason: When butter and sugar are heated together to make toffee, they undergo a chemical transformation. The heat causes the sugar to caramelize and change its molecular structure, forming a new substance (toffee). This process involves a chemical reaction, as new substances are created, and energy is either absorbed or released in the form of heat.
c) Cotton being woven to make sheets: Physical Change
- Reason: The process of weaving cotton into sheets does not alter the chemical structure of the cotton fibers. The fibers simply change shape and arrangement. This is a mechanical process, not a chemical one, since no new substance is formed during the weaving.
d) Coal burning in air: Chemical Change
- Reason: When coal burns in air, it reacts chemically with oxygen to form new substances, such as carbon dioxide and water vapor. This is an example of combustion, a chemical reaction in which the composition of the coal changes, and new compounds are produced. The burning of coal involves a rearrangement of atoms and energy release in the form of heat and light.
In summary:
- Physical changes do not result in the formation of new substances, whereas chemical changes do. The key indicator of a chemical change is the formation of new substances with different properties from the original ones.
