6.2.2-6.2.3

6.2.2 Define the term activation energy (Ea)

Activation energy is the minimum energy required for a reaction to take place 

6.2.3 Describe the collision theory

Three factors affect the rate of reaction:

1. Collision Frequency- The more likely the chance of particles colliding with each other the faster the rate of reaction 
2. Number of particles with greater kinetic energy than activation energy (E>Ea)- For a reaction to take place, the particles must have enough energy to overcome the activation energy of the reaction. Successful reactions take place when the kinetic energy is greater than than the activation energy. This is so that the particles do not repel each other.
3. Collision geometry or orientation- The collision must occur in the correct geometrical alignment, this means that reactive parts of the molecule have to be arranged specifically in a collision to enable a reaction with another particle. (see picture below)

6.2.1 Describe the kinetic theory in terms of the movement of particles whose average energy is proportional to temperature in Kelvin.

Kinetic theory is basically defined by particles which make up chemical elements/compounds are in constant random motion. This are rapidly moving particles which frequently collide with each other and the walls of the container. As both temperature and kinetic energy are proportional, increasing the temperature (in Kelvins) will in turn increase the kinetic energy or the movement of particles.

The picture to the right illustrates the kinetic theory with ball bearings acting as particles, the cylinder and the polystyrene  acting as the container and a motor which generates the heat powered by electricity from the battery pack. Increasing the voltage is an analogy to increasing temperature and from the kinetic theory the ball bearings move faster and collide more frequently with the walls and with each other pushing the polystyrene up accordingly increasing the volume. Not all particles contain the same amount of kinetic energy. An average is taken .

The reason Kelvin is used instead of Celsius is because in 0 degrees Celsius the particles still have kinetic energy. Absolute zero refers to the temperature being -273Kelvin to completely stop the movement of the particles. This has not been achieved yet.

Rate of Reaction

-6.1.1 Define the term Rate of Reaction
The rate of a chemical reaction is a measure of the amount of reactants being converted into products per unit time

-6.1.2 Describe suitable experimental procedures for measuring rates of reactions

-6.1.3 Analyse data from rate experiments. Graphs of changes in concentration, volume or mass against time should be interpreted qualitatively

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