GCSE Chemistry C6 - The Rate and Extent Of Chemical Change

rate of reaction equation

amount of reactant used or product formed/ time

factors which affect the rates of chemical reactions

- concentration

- pressure

- surface area

- temeprature

- catalysts

collision theory

chemical reactions can occur only when reacting particles collide with eachother and with sufficient energy

activation energy

the minimum amount of energy that particles must have to react

increasing concentrationi

increasing the concentration of reactants in the solution, pressure of reacting gases, surface area of solid reactants increases the frequency of collisions and so increases the rate of reaction

increasing temp..

increases the frequency of collisions and makes the collisions more energetic and so increases rate of reactions

catalysts

- substances that speed up chemical reactions without being changed or used up during the reaction

- enzyes act as catalysts in biological systems

- they are not included in the equation for a reaction

- they decrease activation energy which increases the proportion of particles with energy to react

- provide a different pathway for a chemical reaction that has a lower activation energy

reversible reactions

- the products can react to produce the original reactants

- diretion of reversible reactions can be changed by changing the conditions

- the same amount of energy is transferred each way (for one energy will be gained, the other energy will be lost)