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things that affect
the rate (speed) of a reaction		  
 

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genetics . . .. . cell division

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Things that affect the speed of a chemical reaction are . .

surface area of the substances reacting
(the bigger the surface area, the faster the reaction, for instance surface area of a solid is increased by crushing it to make smaller particles, such as in a powder)

 
the concentration of the substances reacting
(dilute solutions react more slowly than concentrated ones)

 
the presence of a catalyst
(a catalyst appears to be unchanged by the reaction that it speeds up)

 
the temperature of the substances that are reacting
(high temperatures tend speed up the rate of reaction)