Chemical Energetics

Question 1

What do particles need to collide with in order for a substance to react

Answer 1

Correct orientation
Sufficient energy

Question 2

What does H mean

Answer 2

Enthalpy
Heat energy

Question 3

What does ΔH mean

Answer 3

Enthalpy change
Amount of energy released or absorbed during a reaction

Question 4

What does Ea mean

Answer 4

Activation energy
Minimum amount of energy colliding particles must have to react

Question 5

Activated complex

Answer 5

High energy state a reaction goes through in order to change reactants into products

Question 6

Describe an effective collision

Answer 6

Reactants have the sufficient activation energy, become an activated complex, form products

Question 7

2 chemical energetics reactions examples

Answer 7

Exothermic and endothermic

Question 8

Exothermic reaction

Answer 8

When energy is transferred to the surroundings so the temperature of the surroundings increase

Question 9

Endothermic reactions

Answer 9

When energy is absorbed from the surroundings so the temperature of the surroundings decrease

Question 10

Examples of Exothermic reactions

Answer 10

Combustion
Oxidation
Neutralisation reactions

Question 11

Examples of endothermic reactions (3)

Answer 11

Thermal decomposition
Photosynthesis
Cold packs for sportinjuries

Question 12

Characteristics of Exothermic reactions (3)

Answer 12

ΔH is negative
Products have less energy than reactants
Energy is released into solution, causing it to warm

Question 13

Draw an Exothermic energy profile/level diagram

Answer 13

Question 14

Characteristics of endothermic reactions (3)

Answer 14

ΔH is positive
Products have more energy than reactants
Energy is absorbed from solution (gets cooler)

Question 15

Draw an endothermic energy profile

Answer 15

Question 16

Draw a practical used to depict exo and endo thermic reactions

Question 17

Describe an Exothermic reaction in terms of bonds

Answer 17

Energy needed to break bonds is less than the energy produced when new bonds are made

Question 18

Describe an endothermic reaction in terms of bonds

Answer 18

The energy needed to break bonds is more than the energy released when new bonds are made

Question 19

What is the bond energy rule

Answer 19

Bond breaking = Endothermic
Bond making = Exothermic

Question 20

How do you calculate the change in Enthalpy and what is the unit

Answer 20

Bond energy of reactants - Bond energy of products
kJ/mol

Question 21

What is room temperature

Answer 21

25 degrees Celsius

Question 22

Does the solution get warmer or cooler in an endothermic reaction and why

Answer 22

Cooler, because energy is absorbed from the solution

Question 23

Does the solution get warmer or cooler in an exothermic reaction and why

Answer 23

Energy is released into the solution so the solution gets warmer

Question 24

Equilibrium definition

Answer 24

State achieved when the forward and reverse reactions occur at the same rate and the concentration of the reactants and products stay constant

Question 25

What happens if you encourage the forward reaction

Answer 25

More product is produced