6.1.3 Rate Graphs

Rate Graphs

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Rate graphs are visual tools used to show how the amount of reactants or products changes over time during a reaction. These graphs help us see how quickly a reaction is happening at different stages.

Understanding the Curves:

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Rate graphs often show curves because the rate of reaction changes as the reaction progresses.

Reactant Curve: If you plot the amount of reactant leftover time, the curve will slope downwards because the reactants are being used up.
Product Curve: If you plot the amount of product formed over time, the curve will slope upwards because more product is being made as time goes on.
Steepness of the Curve:
- At the beginning of the reaction, the curve is steepest because the reaction is fastest here. This is when there are plenty of reactant particles available to collide and react.
- As the reaction continues, the curve becomes less steep because the reactants get used up, so there are fewer particles to collide, slowing down the reaction.
- Eventually, the curve flattens out (plateaus) when the reaction stops, meaning no more reactants are left or the system has reached equilibrium.

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Calculating the Rate of Reaction from a Graph:

To find the rate of reaction at a specific point on a rate graph, you need to calculate the gradient (slope) of the curve at that point.
Drawing a Tangent:
A tangent is a straight line that just touches the curve at a specific point without crossing it.
By drawing a tangent to the curve at the point where you want to find the rate, you can measure the change in the amount (y-axis) over the change in time (x-axis).
Calculating the Gradient:
The gradient (and hence the rate of reaction) is calculated as:

Rate of Reaction=\frac{Change in Amount}{Change in Time}

This gives you the rate of reaction at that specific point in time.

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Example:

If a tangent on a rate graph shows that 10 cm³ of gas is produced over 2 seconds, the rate of reaction at that point is:

Rate of Reaction= \frac{10cm^3}{2s} = :highlight[5cm^3/s]

Rate Graphs Simplified Revision Notes for GCSE AQA Chemistry

6.1.3 Rate Graphs

Rate Graphs

Understanding the Curves:

500K+ Students Use These Powerful Tools to Master Rate Graphs For their GCSE Exams.

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