Module 5, Section 1

Question 1

Define reaction rate

Answer 1

Change in the number of reactants or products per unit time

Question 2

Describe the iodine clock procedure

Answer 2

1) Add sodium thiosulfate and starch to an excess of hydrogen peroxide and iodide ions
2) Starch acts as an indicator, turning blue-black in the presence of iodine
3) Sodium thiosulfate reacts with any iodine
4) Once sodium thiosulfate is used up, any iodine is left in solution, turning it blue-black
5) Varying concentrations of iodide or hydrogen peroxide will alter time for colour change

Question 3

What is a zero order reaction?

Answer 3

Double reactant’s concentration, rate stays the same

Question 4

What is a first order reaction?

Answer 4

Double reactant’s concentration, rate also doubles

Question 5

What is a second order reaction?

Answer 5

Double reactant’s concentration, rate quadruples

Question 6

What can Arrhenius’ equation be converted to?

Answer 6

InK = -Ea/RT + InA
Gradient = -Ea/R
Y-intercept = InA, so e

Question 7

What is a homogenous reaction, and what is included in the Kc expression?

Answer 7

All reactants and products in the same state, all included in Kc expression.

Question 8

What is a heterogenous reaction and what is included in Kc expression?

Answer 8

Reactants and products in different states, only gases and liquids included in equilibrium constant expression.