Physical Reactions
Science: KS3, topic 3.5.1
Conservation of Mass
In a chemical reaction, no mass is lost or gained during the reaction. Mass is also conserved during a physical reaction.
Conservation of mass
- A chemical reaction is when atoms of the starting reactants rearrange.
- In a chemical reaction, the mass of the reactants equals the mass of the products.
Mass in physical reactions
- In a physical reaction, there is no rearrangement of atoms.
- So the mass will also be the same.
Physical reactions
- A change of state is an example of a physical reaction.
- The mass at the start will be the same as the mass at the end.
Other physical reactions
- Other physical reactions include:
- Dissolving sugar into a cup of tea.
- A melting ice cream.
- Boiling the kettle to make a hot chocolate.
Test yourself on Physical Reactions
When is mass conserved?
Which of these is NOT an example of a physical reaction?
Which is true of chemical reactions?
A chemical reaction happens inside a sealed container, so nothing can enter or leave. What happens to the total mass inside the container during the reaction?