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| Question | Answer |
| What is the key feature of a physical change? | A key feature of a physical change is that no new substance is produced during the change. |
| What do physical changes include? | Physical changes include: -a change in shape or form -expansion and contraction -mixing substance together -a change of state |
| Why can physical changes be easily reversed? | The physical properties of the substances change but the substance before and after the change is exactly the same. Therefore, physical changes can be reversed easily |
| What is the simplest example of a physical change? | The simplest example of a physical change is one that changes the shape or form of a substance. |
| When else does a physical change occur? | Physical changes also occur when the temperature of a substance increases or decreases. |
| What happens to solids, liquids and gases when they are heated? | When solids, liquids and gases are heated they expand and take up more space. |
| What happens when expansion occurs? | The volume of the object increases and its density decreases but no new substances are formed. |
| What happens when a solid, liquid or gas is cooled? | When a solid, liquid or gas is cooled, it contracts. |
| What happens when contraction occurs? | When contraction occurs, the volume of the substance decreases and its density increases. |
| What happens if enough heat is applied to a substance? | If enough heat is applied ta a substance, then it will not only expand but will also change state from a solid to a liquid or from a liquid to a gas. |
| Solid - Liquid | Melting |
| Liquid - Gas | Evaporation |
| Gas - Liquid | Condensation |
| Liquid - Solid | Freezing / Solidification |
| Solid - Gas | Sublimation |
| Gas - Solid | Deposition |
| What is a solution? | When a solid is dissolved into a liquid, they form a solution. |
| What is crystallization? | Crystallization is the evaporation of a solvent from a solution to leave solute behind as crystals. |
| How can you distinguish between a chemical and a physical change? | You have to determine if a new substance has formed as a result. |
| How can you detect the presence of a new substance? | You can detect a new substance by: -seeing a change in colour -smelling a gas or seeing bubbles -seeing a new solid forming in a clear solution -seeing light or feeling a change in temperature |
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