Topic 6 - The Rate and Extent of Chemical Change

What is the Rate of Reaction?

It is the rate of how fast the reactants are changed into products.

Describe a graph of rate of reaction?

See Image:

Explain Collision Theory?

Surface Area Increased (Smaller Pieces) = Greater SA : Volume = Greater area for collisions

Higher Concentration/Pressure = More Particles / cm³

Greater Temp = Particle Kinetic Energy Increase

Greater number of particles/cm³ or Kinetic Energy or Area for collisions, therefore increases number of successful collisions

How does a Catalyst affect Rate/Collisions?

A catalyst increases the rate of reaction by providing a pathway to particles with a lower activation energy.

What is the formula for Rate of Reaction?

Rate = Amount of Reactant used or Amount of Product formed / Time

What are three ways to measure rate?

1. Precipitation and Colour Change - Visual change for solution to cloud and block cross experiment. (Sodium Thiosulfate and HCL)

2. Change in Mass - Mass leaving from experiment measured regularly. (Magnesium and HCL)

3. Volume of Gas given off - Gas syringe measure gas given off.

How to calculate the mean rate of reaction?

Graph Given

Change in Y / Change in X

Finding Rate of Reaction at a point using a tangent?

See Image:

What is a Reversible Reaction?

A reaction where the products can react again to make the reactants.

What is Equilibrium?

The point at which the rates of the forward and backward reactions in a reversible reaction are the same, and so the amounts of reactants and products in the reaction container don’t change. Only in a closed system.

What is Le Chatelier’s Principle?

It is the idea that if you change the conditions of a reversible reaction at equilibrium, the system will try to counteract the change.

What are 3 changes that can be counteracted?

1. Temperature - Equilibrium will move to decrease/increase it.

2. Pressure - Equilibrium will move to decrease(move to more molecules)/increase(move to less molecules) it.

3. Concentration - Equilibrium will move to increase reactants/products it.