General overview (rates of reaction and energy change)

Formula for rate of reaction

Rate of reaction=amount of reactant used or product formed/time

How do reactions occur and how can the rate be increased?

Reacting particles collide with a specific amount of energy (the activation energy) - to increase the rate, the frequency or energy of collisions must also increase so that more reach the activation energy

How can the rate of reaction be increased?

Increasing temperature, pressure, concentration, surface area, or using a catalyst

How does increasing temperature affects the rate of a reaction?

Particles have more kinetic energy so collisions will happen more often. More particles will have the required activiation energy

How can a greater surface area affect the rate of a reaction?

More particles are exposed so there are more successful collisions

How does increasing concentration affect the rate of reaction?

There are more reacting particles in the same volume, so more frequent collisions will occur

How do catalysts affect the rate of a reaction?

They provide an alternate reaction pathway with a lower activation energy, so more particles will have enough energy to react so there are more successful collisions

What is a catalyst?

A substance that speeds up a chemical reaction without altering the products or being used up in a reaction

What is an enzyme?

A biological catalyst

What enzyme is used in making alcohol?

Yeast

Are neutralisation reactions endothermic or exothermic?

Exothermic

Are displacement reactions endothermic or exothermic?

both

Is a salt dissolving endothermic or exothermic?

Both

Are precipitation reactions endothermic or exothermic?

Exothermic

What is an exothermic reaction?

A reaction where energy is given out

What is an endothermic reaction?

A reaction where energy is taken in

What type of reaction is breaking chemical bonds?

Endothermic

What type of reaction is forming chemical bonds?

Exothermic

When is the overall heat energy for a reaction exothermic?

If more heat energy is released in forming bonds in products than is required in breaking bonds in reactants

When is the overall heat energy for a reaction endothermic?

If less heat is released (heat is taken in) in forming bonds in the products than if required in breaking bonds in reactants

Formula for energy change

Energy change=total energy of broken bonds-total energy of bonds made