Rates of Reaction

This lesson covers:

  1. How to measure & calculate the rate of a reaction
  2. How to interpret the rate of a reaction from a graph
Image showing iron oxide rusting on a metal surface.

Iron can react with oxygen to form iron oxide. This is also known as rusting. 


Is this a fast or slow chemical reaction? 

Fast

Slow

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Illustration of a burning match showing a chemical reaction.

When you strike a match it causes a tiny amount of red phosphorus to be converted to white phosphorus, which then ignites spontaneously in air.


Is this a fast or slow chemical reaction? 

Fast

Slow

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To measure the rate of a reaction, we can either measure how fast the  are being used up, or how fast the  are being formed.

reactants
products

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Which of the following are the equation(s) to calculate the overall rate of a reaction?

(Select all that apply)

Rate of reaction = quantity of products formed x time taken
Rate of reaction = time takenquantity of reactants used​
Rate of reaction = quantity of reactants used x time taken
Rate of reaction = time takenquantity of products formed​

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Which of the following could be units for the rate of a reaction?

(Select all that apply)

m/s

mol/s2 

cm3/s

g/min

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Illustration of magnesium reacting with dilute hydrochloric acid in a beaker.

0.4 g of magnesium reacts completely with dilute hydrochloric acid in 1 min 20 s. What is the overall rate of the reaction? Give your answer in g/s.

0.005

g/s

g/s

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Mg + 2HCl ➔ MgCl2 + H2


90cm3 of hydrogen gas was produced after 5 mins. What is the overall rate of reaction? Give your answer in cm3/s.

0.3

cm3/s

cm3/s

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Graph showing the volume of product produced over time in seconds.

What would the units of the y-axis be?

s

g

mol

cm3

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Graph showing the change in quantity of a substance over time during a reaction.

The above graph shows how the quantity of a substance changes over the course of a reaction. Is the substance a reactant or a product?

Reactant 

Product

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Graph showing the volume of hydrogen produced over time in a reaction between sodium and hydrochloric acid.

Sodium reacts with hydrochloric acid to form sodium chloride and hydrogen gas:


2Na + 2HCl ➔ 2NaCl + H2


The graph above shows how the quantity of hydrogen produced changed over time. Describe and explain the shape of the graph.

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