Chemistry paper 2

What is the rate of reaction?

How quickly reactants are used up or products are produced

What is the equation for calculating the mean rate of reaction?

Mean rate = Change in quantity of product or reactant / time taken

What is the unit for rate of reaction in a reaction involving a change in mass?

g/s

What is the unit for rate of reaction involving a change in volume?

cm3/s

What is the activation energy?

The minimum amount of energy colliding particles need to have before a reaction will take place

What effect does increasing concentration have on the rate of reaction?

increase

Why does increasing concentration have this effect on the rate of reaction?

More reactant particles in the same volume lead to more frequent collisions

What effect does increasing pressure have on the rate of reaction?

Increases

Why does increasing pressure have this effect on the rate of reaction?

There is less space between particles means more frequent collisions

What effect does increasing surface area have on the rate of reaction?

Increases

Why does increasing surface area have this effect on the rate of reaction?

More reactant particles are exposed and able to collide, leading to more frequent collisions

What effect does increasing temperature have on the rate of reaction?

Increases

Why does increasing temperature have this effect on the rate of reaction?

Particles move faster, leading to more frequent collisions - particles have the same activation energy so more collisions result in a reaction

What is a catalyst?

A substance that increases the rate of reaction but is not used up in the reaction

How do catalysts increase the rate of reaction?

Lower the activation energy of the reactions, so more collisions result in a reaction

What is a reversible reaction?

When the reactants turn into products and the products turn into reactants

What is dynamic equilibrium?

The point in a reversible reaction when the rate of the forward and reverse reactions are the same

What are the three reaction conditions that can be changed?

Concentration, temperature, pressure

What is Le Chatelier’s principle?

The position of equilibrium will shift to oppose external changes

What is the effect of increasing the concentration of reactants on a reactant at dynamic equilibrium?

Favours the forward reaction

What is the effect of decreasing the concentration of products at dynamic equilibrium?

Favours the forward reaction

What is the effect of increasing pressure on a reaction at dynamic equilibrium?

Favours the reaction that leads to the fewest molecules

What is the effect of decreasing pressure on a reaction at dynamic equilibrium?

Favours the reaction that leads to the most molecules

What is the effect of increasing temperature on a reaction at dynamic equilibrium?

Favours the endothermic reaction

What is the effect of decreasing temperature on a reaction at dynamic equilibrium?

Favours the exothermic reaction

What is a hydrocarbon?

A compound containing only carbon and hydrogen

How is crude oil formed?

Over millions of years from the remains of ancient biomass

What are alkanes?

Hydrocarbons that only contain single bonds

What are the first four alkanes?

Methane, ethane, propane, butane

What is the general formula for alkanes?

C(n)H(2n+2)

How does boiling point depend on alkanes chain length?

A longer chain has a higher boiling point