# Rates of reaction

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• RATES OF REACTION
• RATE = how FAST a reaction goes (speed)
• to measure the change over a period of time
• Graph
• The curve is steepest at the start so the reaction is fastest then (its rate is greatest
• The slope keeps changing until the curve flattens out which tells us that the rate of the reaction keeps changing
• The curve becomes less steep as time passes, showing that the reaction is slowing down
• The slope of the curve tells you how fast the reaction is going
• When the curve goes flat, it means that the reaction has stopped. The reaction rate is zero
• Average rate of reaction (in cm   per min or sec) = total volume of gas collected (in cm  ) divided by total time taken (in min or sec)
• Ways to change the rate of reaction
• by changing the particle size
• using a catalyst
• for example using manganese oxide
• Catalysts in industry
• When making ammonia, iron (a catalyst) is used.
• Reduces fuel bills
• by changing the temperature
• If you increase any of these the rate will increase, and if you decrease them then the rate will decrease
• by changing the concentration
• by changing the particle size
• by changing the concentration