FUNCHEM 15 - Rate laws & orders of reactions I

Question 1

How many methods are there to determine reaction order?

Answer 1

There are three methods that can be used to determine reaction order: 1. initial rates method (differential rate law) 2. graphical method (integrated rate law) 3. half-life method

Question 2

Based on the integrated law, for which reaction orders is the half-life dependent and independent.

Answer 2

Half-life is dependent on the concentration of reactants for zero order and second order reactions, therefore the half-life is not constant throughout the reaction. Half-life is independent of the concentration of reactants for first order reactions, therefore the half-life is constant throughout the reaction.

Question 3

How can you identify if a reaction is first order?

Answer 3

If 50% reduction cycles in concentration occur at regular time intervals, this means the half-life is constant and that the reaction is first order.

Question 4

For the graphical method, what do the graphs look like when plotted against different sets of data for each reaction order?

Answer 4

Zero order: line / curve / curve First order: curve / line / curve Second Order: curve / curve/ line

Question 5

Write the Differential Law, Integrated Law, and Half-life Law for each reaction order.

Answer 5