rates of reaction

Rate of Reaction

the speed at which a chemical reaction occurs.

Two common ways:

1.Measure how fast the products are formed

○Colour change

○Gas formation

2.Measure how fast the reactants are used up

Effective collision

When the particles collide with enough kinetic energy and the correct orientation to break the bonds between particles so new bonds can form.

ineffective collisoin

Collisions can occur and yet result in no reaction if there is insufficient energy or incorrect orientation.

activation energy

The minimum amount of energy needed for the particles to react - if particles collide with less energy than the activation energy, they will not react

minimum amount of energy required by the colliding reactant particles for a reaction to occur

concentration

Increasing the concentration of a reactant increases the number of particles per unit volume. This increases the frequency of collisions, and therefore, the frequency of successful collisions, which increases the rate of the reaction.

surface area

Increasing the surface area of a reactant increases the number of particles immediately available to react. This increases the frequency of collisions, and therefore, the frequency of successful collisions, which increases the rate of the reaction.

temperature

Increasing temperature increases the kinetic energy of the particles. This increases the rate of reaction in two ways…

1.Particles move faster, increasing the frequency of collisions and, therefore, the frequency of successful collisions.

2.Particles collide with more energy which means more collisions will be above activation energy. This increases the frequency of successful collisions which also increases the rate of reaction.

catalyst effect

catalysts provide an alternative reaction pathway with a lower activation energy

catalyst ROR 

this means a greater proportion of collisions will have suffiient energy to overcome activation energy. Therefore there will be more frequenc successful collisions and a faster rate of reaction

theya re involeved in the rreaction but are not actually used up - intherory can be recovered and reused

Particle theory

Particle theory states that all matter is made up of very small particles (atoms, ions or molecules) and these particles are in constant motion. Temperature affects the speed of the particles (i.e. when the temperature increases the speed of the particles also increases)

collision theory

Collision theory

In order for a chemical reaction to occur, two or more reactant particles must collide with sufficient force (energy) and at the correct orientation. The minimum amount of energy required for a chemical reaction to proceed is called the activation energy.

Acids

Acids are hydrogen containing compounds that give H+ ions or protons on dissociation in water (proton donors)

Bases

Bases are hydroxide compounds which give oh- ions on dissociation in water (proton acceptors)

pH

pH reflects the concentration of H3O+ ions in solution. The higher the pH, the lower the [H3O+].

or, the higher the [H3O+] the lower the [OH-] in solution

Electrical Conductivity

Charged particles that are free to move are needed to conduct electricity.