Chemistry - Ch 2
Created by anishahegde
| Term | Definition |
|---|---|
slow changes | changes that happen over a long period of time. |
fast changes | changes that happen in a short interval of time. |
natural changes | changes that take place in nature without human intervention. |
man- made changes | changes that take place due to the efforts of human beings.
|
periodic changes | |
non periodic changes | Changes that are not repeated at regular intervals and can occur at any time. |
periodic changes | Changes that are repeated after a fixed interval of time and not randomly. |
reversible changes | when a change in a substance can be reversed by chphanging the conditions. |
irreversible changes | happens if a substance cannot be brought to its original state after a change. |
physical changes | it is a change in which a substance changes temporarily in some or all physical properties. |
characteristics of a physical change | 1. No new substance is formed.
2. The changes are most often temporary and can be reversed by changing the conditions.
3. There is no change in mass
4. There is usually no gain or loss of energy.
5. No change in chemical composition.
6. The change is only in size, shape, texture, colour, or smell of the substances |
chemical change | in a chemical change the original substance gives rise to one or more new substances with entirely different compositions and properties. |
characteristics of a chemical change | 1. new substance is formed
2. the composition of the substance is changed completely
3. the change is permanent and irreversible
4. there is a change in mass from the original substance.
5. there is an exchange of energy. |
endothermic reaction | energy is taken in and used for the reaction |
exothermic reaction | energy is given out during the reaction |
carbon disulphide | liquid in which sulphur can be dissolved in |
why do balloons burst when kept near a heat source | The air particles inside the balloon heat up and gain kinetic energy. Hence, they move faster and start to spread. This exerts pressure on the balloon's inner walls, and when the elastic limit is reached, the rubber stretches and the balloon bursts. |