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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
