Difference between revisions of "Chemical Reaction"
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===About Chemical Reactions=== | ===About Chemical Reactions=== | ||
| + | : Most '''chemical reactions''' are irreversible. | ||
: In a '''chemical reaction''' the [[atom]]s rearrange to form a new [[substance]]. | : In a '''chemical reaction''' the [[atom]]s rearrange to form a new [[substance]]. | ||
: '''Chemical reactions''' often need some [[energy]] to start, like [[combustion]] where the [[fuel]] needs to be [[Heat|heated]] to start. | : '''Chemical reactions''' often need some [[energy]] to start, like [[combustion]] where the [[fuel]] needs to be [[Heat|heated]] to start. | ||
| − | : If a '''chemical reaction''' gives off more energy than it needs to start then it is called an [[Exothermic Reaction]]. | + | : If a '''chemical reaction''' gives off more energy than it needs to start then it is called an [[Exothermic Reaction]]. In these '''reactions''' the [[temperature]] increases. |
: If a '''chemical reaction''' takes in more energy than it gives out then it is called an [[Endothermic Reaction]]. | : If a '''chemical reaction''' takes in more energy than it gives out then it is called an [[Endothermic Reaction]]. | ||
| + | In these '''reactions''' the [[temperature]] decreases. | ||
===Examples=== | ===Examples=== | ||
Revision as of 16:38, 23 September 2018
Contents
Key Stage 2
Meaning
A chemical reaction is when one substance changes into another.
About Chemical Reactions
- Most chemical reactions are irreversible.
- Chemical reactions usually cause a change in temperature.
- Chemical reactions you should know are:
Key Stage 3
Meaning
A Chemical Reaction is when the atoms in molecules break their bonds and form new bonds, usually with other atoms.
About Chemical Reactions
- Most chemical reactions are irreversible.
- In a chemical reaction the atoms rearrange to form a new substance.
- Chemical reactions often need some energy to start, like combustion where the fuel needs to be heated to start.
- If a chemical reaction gives off more energy than it needs to start then it is called an Exothermic Reaction. In these reactions the temperature increases.
- If a chemical reaction takes in more energy than it gives out then it is called an Endothermic Reaction.
In these reactions the temperature decreases.