4.1.1 Chemical Reactions

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• Middelbare school
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• Leerjaar 3

Chemical Reactions

Chemical Reactions

Reactants dissapear and reaction products are formed

The formation of a new substance (the reaction product), a colour change or a shift in temperature is often a telltale sign that a chemical reaction has happened.

Each chemical reaction starts out with certain molecules and ends with different types of molecules.

The atoms which make up the molecules on both side will be the same on both sides, they get reorganised into other molecules. 

Because the number and type of atoms are the same before and after the reaction the total mass of all substances before and after remains the same. (do make certain you take gases into consideration)

Energy

A chemical reaction is either Exothermic or Endothermic. Both reactions will require energy to get started.

After the start the exothermic reaction will provide itself with more energy, and will only stop when one or more of the starting substances are not available anymore.

After the start the endothermic reaction will require energy constantly to keep on going, without the energy it will stop.

examples of
exothermic reactions

examples of
endothermic reactions

Rotting fruit

Explosions

There are multiple factors that influence reaction speed, which can you think of?

Reaction speed

There are five factors which influence the speed of a reaction.

1. Temperature of the substances
2. Surface area of contact between the substances
3. Concentration of the substances (pure/diluted for instance)
4. Type of reactant
5. A catalyst (substance which improves reaction speed but does not react itself)