Rates of Reactions

Factors affecting the rate of reaction The surface area The concentration of the reactant The temperature at which the reaction is carried out The use of a catalyst The influence of light

1. Rates of Reaction - Surface Area The more finely grated/powdered a solid is the faster it reacts. Increased surface area

Limestone reacted with hydrochloric acid Calcium carbonate + hydrochloric acid calcium chloride + water + carbon dioxide

Rate of Reaction The reaction is faster at the start. The gas is produced faster with the smaller marble chips – increased surface area. The loss of mass is the same. At the end the loss of mass slows down as the reactants are used up.  

2. Concentration of Reactant Magnesium and hydrochloric acid magnesium chloride + hydrogen

Rates of Reaction - Concentration The curve is steeper for the higher concentration – it is faster. The total volume of hydrogen produced at the end is the same.

3. Rates of reactions - Temperature A reaction can be made to go faster or slower by changing the temperature. Food is stored in a fridge to decrease the rate of decay/oxidation. Sodium thiosulfate + hydrochloric acid sodium chloride + sulfur + sulfur dioxide + water http://www.youtube.com/watch?v=CH8gH7xKCxQ

Effect of Temperature The rate of a reaction increases when the temperature is increased.

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