How do chemists control the rate of reactions? - OCR 21st CenturyRate of reaction
Rate of reaction is a measure of how fast a reaction takes place. In industry, chemists control rates of reaction to ensure the production is safe but still fast enough to keep up with demand.
The rate of a reaction is a measure of how quickly a reactantA substance that reacts together with another substance to form products during a chemical reaction. is used up, or a productA substance formed in a chemical reaction. is formed. Rate of reaction is affected by factors such as concentrationThe concentration of a solution tells us how much of a substance is dissolved in water. The higher the concentration, the more particles of the substance are present., pressureForce exerted over an area. The greater the pressure, the greater the force exerted over the same area., temperatureHow warm or cold something is. and surface areaThe total area of exposed material available for a chemical reaction (or absorption) to take place. to volumeThe 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. ratio of a solid reactant.
A model of colliding particleA general term for a small piece of matter. For example, protons, neutrons, electrons, atoms, ions or molecules. helps to explain why different factors affect rate of reaction.
Collision theory
For a chemical reaction to happen:
reactant particles must collide with each other
the particles must have enough energy for them to react
A collision that produces a reaction is called a successful collisionA collision between reactant particles that has enough energy for a reaction to happen.. The activation energyThe minimum amount of energy that colliding particles must have for them to react. is the minimum amount of energy needed for a collision to be successful. This is different for different reactions.