Rates of reactions

What is a molecule

two or more atoms bonded together

Polyatmoic ion

An ion that is made of more then one atom

What is combustion?

Reaction that involves oxygen and fuel

What is the name given to the chemicals that react with oxygen to produce energy?

Fuels

Atom

Basic unit of matter that include subatomic particles of protons, neutrons and electrons

reactant

a substance that takes part in and undergoes change during a reaction.

product

A substance produced in a chemical reaction

energy

The ability to do work or cause change

Exothermic reaction

a chemical reaction that releases energy/heat to its surroundings

Exothermic reaction graph

reactants higher than products

endothermic reaction

A reaction that ABSORBS energy in the form of heat

endothermic reaction graph

products higher than reactants

Complete combustion

A combustion reaction in which the only products are carbon dioxide and water

Incomplete combustion

When a fuel burns in insufficient oxygen, producing carbon monoxide as a toxic product.

Respiration

The process by which cells break down simple food molecules to release the energy they contain.

aerobic respiration

Respiration that requires oxygen and occurs in plant and animal cells

anaerobic respiration

Respiration that does not require oxygen

examples of exothermic reactions

combustion, oxidation, neutralisation

examples of endothermic reaction

photosynthesis

colision theory

chemical reactions only occur when reactant particles collide with sufficient energy (activation energy) and correct orientation.

Variables for rates of reaction

Surface area

Concentration

Heat or temperature

Mixing or stirring

presence of a catylyst

Surface area - rates of reactions

The larger the surface area, the more particles available for collisions.

Concentration - rates of reactions

The more particles in a solution, the more likely it is that collisions will occur.

Heat of temperature - rates of reactions

The higher the temperature, the more energy the particles have, so the more they move around and the more likely they are to collide.

Mixing of stirring - rates of reactions

Mixing or stirring increases movement of the particles, making them more likely to collide.

Presence of a catalyst - rate of reactions

A catalyst is a 'helper' molecule that brings the reactant particles together in the correct orientation, but is not actually apart of the reaction itself. It can be reused over and over. While a catalyst does not increase the rate of reaction, it does lower the activation energy, which means the reaction will take place at a lower temperature.

Mean rate of reaction =

Mean rate of reaction = quantity of reactant/product over time

What is concentration

Concentration is the NUMBER of PARTICLES in a certain VOLUME.