Chemical reactions vary in speed. The rate of reaction measures how much product is made in a given time. For reactions to occur, reactant particles must collide.
The rate of reaction can be found by measuring the amount of productA substance formed in a chemical reaction. formed in a certain period of time. The massThe amount of matter an object contains. Mass is measured in kilograms (kg) or grams (g). of a solid product is often measured in grams, while the 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. of a gaseous product is often measured in cm3.
The time period chosen may depend upon the rate of the reaction. For example, it may be a few seconds for a fast reaction or a few minutes for a slow reaction.
The units for rate of reaction are commonly written as:
g/s or g/min
cm3/s or cm3/min
There are three main methods of measuring rate:
measuring the volume of gas given off by a reaction over time
measuring the loss of mass of a reaction over time when a gas is produced
measuring the amount of light that passes through a reaction mixture (as a precipitate forms) over time – this can be done by inspection or using a light sensor and data logger
