Rate of Reaction (Graphs & Factors) & Collision Theory

What is the rate of a chemical reaction?

The quantity of reactant used up or quantity of product formed per unit time.

What equation is used to calculate mean rate of reaction?

Mean rate = quantity of reactant used / time taken OR quantity of product formed / time taken

What units can be used for rate of reaction?

g/s when measuring mass and cm³/s when measuring gas volume.

How can rate be measured experimentally?

Measure the change in quantity of a reactant or product over time, for example: volume of gas produced -- loss of mass -- colour/turbidity change.

What does a steep gradient on a reaction graph mean?

A faster rate of reaction.

What does a shallow gradient on a reaction graph mean?

A slower rate of reaction.

What does it mean when a product–time graph becomes horizontal?

The reaction has stopped because a reactant has been completely used up, so no more product is being formed.

How do you calculate mean rate from a graph?

mean rate = change in quantity / change in time

How do you calculate the rate at a specific point on a curved graph?

Draw a tangent to the curve at that point. -- Choose two widely separated points on the tangent. -- gradient - change in y / change in x

What five factors affect the rate of a chemical reaction?

Concentration of reactants in solution -- Pressure of reacting gases -- Surface area of solid reactants -- Temperature -- Presence of a catalyst

What does collision theory state?

Chemical reactions occur only when reacting particles collide with each other with sufficient energy.

What is activation energy?

The minimum amount of energy that particles must have to react.

What is a successful collision?

A collision between reacting particles with sufficient energy to react.

What determines the rate of a reaction according to collision theory?

The frequency of successful collisions between reacting particles.