Chapter 1:Unit 6. Physical and Chemical Properties and Change
Physical and Chemical Properties and Change
Physical Properties are those that can be observed or measured without changing the composition of the materials. Physical properties are determined by a substance’s outside appearance. Chemical properties are those that determines how a substance can be converted to another substance. A substance reacting ability is defined by chemical properties.
A physical change alters a substance’s shape, state without changing its original composition. A Chemical change or a chemical reaction converts one materials to another and therefore a totally new substance is formed with its own new properties and structures. In physical change original substances can be separated or recovered applying some physical methods like filtration, distillation etc. In chemical change, since new compounds are formed, only chemical method can be applied to obtain original substances.
Preparing smoothie or boiling water would be an example of physical change.
Whereas, rusting on iron, digestion of food in our body, electrolysis of water are examples of chemical change.
Chemical change
Watch this out
Questions:
- When a chunk of dry ice (solid CO2) is placed out in the air, the solid gradually disappears and a gas is formed above the solid. Does it indicate that a chemical or physical change has occurred?
- Characterize each process as a physical change or a chemical change
a) making ice cubes from water
b) burning natural gas
c) silver jewelry tarnishing
d) a pile of snow melting
e) fermenting grapes to produce wines
Ans: 1. Physical change
2.a) physical change
b) chemical change
c)chemical change
d) physical change
e) chemical change
