Reaction Rates

List the factors that may affect the rate of a chemical reaction

• concentration (solutions or gases)

• temperature

• catalyst

• surface area

• pressure (only gases)

What must happen for a chemical reaction to occur?

particles must collide in the correct orientation with sufficient energy (activation energy)

How can the pressure of a gas also be increased without decreasing the volume of a container?

having more molecules/particles in the same space

List the steps for this method

• hydrogen peroxide added to conical flask and bung is replaced

• record initial volume of gas in measuring cylinder

• manganese dioxide catalyist quickly added to conical flask and bung is replaced

• start stop clock simultaneously

• record volume of gas produced in measuring cylinder at regular intervals

• reaction complete when no more gas is produced

List the steps for this method

• measure 10g of calcium carbonate using a mass balance, measure by difference

• measure out 250cm³ HCl using measuring cylinder

• add HCl to conical flask

• place conical flask to balance, zero balance

• add calcium carbonate to conical flask

• start stop watch

• measure mass loss every 10s

• plot a graph, mass loss (y axis) vs time (x axis)

• draw tangents to calculate rate at different times by calculating gradient

What is the activation energy?

What is the activation energy?

Increase in temperature, increases the rate of reaction, explain why

• at higher temperatures T2

• more molecules have E>Ea

• more successful collisions per unit time 

• rate increases

How does a catalyst affect the reaction rate?

• with catalyst, more molecules have E > Ea

• more frequent successful collisions

• rate increases

What is a homeogeneous catalysis?

the catalyst is in the same state as the reactants

What is a heterogeneous catalysis?

the catalyst is in a different state from the reactants

Why are catalysts used in industrial processes?

• increase sustainability by allowing lower operating temperatures to be used

• reduces energy demand needed from combustion of fossil fuels

• reducing carbon dioxide emissions