Chemical And Physical Changes Flashcards
Definition of a chemical change
Chemical change is a permanent and irreversible change through which the chemical properties of a substance change and one or more new substances are created
Examples of a chemical change
- burning paper
- frying an egg
- rusting if iron
Definition of physical change
A Physical change is when the properties of a substance such as state, size, colour and shape change, but the chemical part properties remain the same. This means that new products are not created during a physical change
Examples of a physical change
- ice melting
- breaking glass
- mixing sand with water
Examples that a physical changes have occurred
Melting
Volume change
Density change
Examples that chemical changes have occurred
New substances are created
Change in colour
Change in smell
Change of temperature
Explain chemical and physical changes in terms of particles.
In a physical change the nature of the substance, the particles of which it is composed and the numbers of particles remain unchanged. In a chemical change the properties of the new substances are different from the original, the particles are different and the number of particles can change.
Why can a chemical change generally not be reversed
In a chemical change, the bonds between a substance are broken/formed, leading to new substances with new properties being formed, leading chemical changes to typically by irreversible
How do you know that a chemical change has occurred
It is irreversible
New substance is created
