Question

Water has both physical and chemical properties’. Support the statement with
examples

Answer 1

Physical Change
Physical changes are changes in which no bonds are broken or formed. This means that the same types of compounds or elements that were there at the beginning of the change are there at the end of the change. Because the ending materials are the same as the beginning materials, the properties (such as color, boiling point, etc) will also be the same. Physical changes involve moving molecules around, but not changing them. Some types of physical changes include:

Changes of state (changes from a solid to a liquid or a gas and vice versa)
Separation of a mixture
Physical deformation (cutting, denting, stretching)
Making solutions (special kinds of mixtures)


Chemical Change
Chemical changes occur when bonds are broken and/or formed between molecules or atoms. This means that one substance with a certain set of properties (such as melting point, color, taste, etc) is turned into a different substance with different properties. Chemical changes are frequently harder to reverse than physical changes.

One good example of a chemical change is burning a candle. The act of burning paper actually results in the formation of new chemicals (carbon dioxide and water, to be exact) from the burning of the wax. Another example of a chemical change is what occurs when natural gas is burned in your furnace. This time, on the left we have a molecule of methane, CH4
CH
4
, and two molecules of oxygen, O2
O
2
, while on the right we have two molecules of water, H2O
H
2
O
, and one molecule of carbon dioxide, CO2
CO
2
. In this case, not only has the appearance changed, but the structure of the molecules has also changed. The new substances do not have the same chemical properties as the original ones. Therefore, this is a chemical change.