Rates and temperature
The greater the The total number of times an event occurs. of A collision between reactant particles that has enough energy for a reaction to happen., the greater the rate of reaction. If the How warm or cold something is. of the reaction mixture is increased:
- A substance that reacts together with another substance to form products during a chemical reaction.A general term for a small piece of matter. For example, protons, neutrons, electrons, atoms, ions or molecules. move more quickly
- the The capacity of a system to do work or the quantity required for mechanical work to take place. Measured in joules (J). For example, a man transfers 100 J of energy when moving a wheelbarrow. of the particles increases
- the frequency of successful collisions between reactant particles increases
- therefore the rate of reaction increases
Note that the mean energy of the collisions changes when the temperature changes:
- the frequency of collisions increase
- the proportion of collisions that are successful also increases
Question
Explain what is meant by a 'successful' collision.
A collision between reactant particles with enough energy (the activation energy or more than the activation energy) to produce a reaction.
Graphs
The rates of two or more reactions can be compared using a graph of The amount of matter an object contains. Mass is measured in kilograms (kg) or grams (g). or The volume of a three-dimensional shape is a measure of the amount of space or capacity it occupies, eg an average can of fizzy drink has a volume of 330 ml. of A substance formed in a chemical reaction. formed against time. The graph shows this for two reactions.
The Another word for steepness. On a graph, the gradient is defined as being the change in the 'y' value divided by the change in the 'x' value. It defines how steep a line is. of the line is equal to the rate of reaction. The faster reaction at the higher temperature:
- gives a steeper line
- finishes sooner