Energy And Equlibrium

Question 1

What happens when bonds are broken?

Answer 1

Energy is taken is in

Question 2

What happens when bonds are formed?

Answer 2

Heat energy is given out

Question 3

What is an exothermic reaction?

Answer 3

A chemical reaction that gives out heat energy

Question 4

What is an endothermic reaction?

Answer 4

A chemical reaction that takes in heat energy

Question 5

Examples of exothermic reactions are?

Answer 5

Neutralisation
Combustion
Displacement reactions
Dissolving
Hydration

Question 6

Examples sod endothermic reactions are?

Answer 6

Thermal decomposition
Photosynthesis
Dissolving
Electrolysis
Thermal cracking of hydrocarbons

Question 7

Explain how the energy within an exothermic reaction changes as the reaction progresses and how it looks on a graph.

Answer 7

Look in book
The products are below the reactants as they have less energy

Question 8

Explain how the energy within an endothermic reaction changes as the reaction progresses and how it looks on a graph.

Answer 8

Look in book
The Products are above the reactants as they have more energy

Question 9

How do you calculate energy change in a chemical reaction?

Answer 9

Energy change = Energy taken in to break bonds - Energy released when new bonds are formed

Question 10

What is the definition of reversible?

Answer 10

A reaction which goes in both the forward and backward directions

Question 11

What is the definition of dynamic equilibrium?

Answer 11

The rate of the forward reaction is equal to the rate of the backward reaction and the amounts of reactant and product remain constant

Question 12

What is the definition of homogeneous?

Answer 12

A reaction in which all the reactants and produce that are produced are in the same physical state

Question 13

What is Le Chatlier’s principle?

Answer 13

If a dynamic equilibrium is distributed by changing the conditions, the position of equilibrium moves to counteract the change.

Question 14

What is the affects of changing the pressure in a closed homogenous system?

Answer 14

If more of a chemical is added the equilibrium position moves to remove it

If some of a chemical is removed, the equilibrium position moves to make more of it

Question 15

What are the affects of changing the pressure in a closed homogeneous system?

Answer 15

To increase the pressure, the position of the equilibrium moves to the side with the most gas molecules and vice versa to decrease the pressure

Question 16

What are the affects of changing the temperature in a closed homogeneous system?

Answer 16

Increasing the temperature of a system in dynamic equilibrium favours the endothermic reaction as it counteracts the change by absorbing more heat

Decreasing the temperature of a system in dynamic equilibrium favours the exothermic reaction as it counteracts the change by producing more heat

Question 17

What is a closed system?

Answer 17

Where no substances can get in or out

Question 18

What is the Haber process?

Answer 18

Combines nitrogen from the air with hydrogen derived mainly from natural gas (methane) into ammonia.

The reaction is reversible and exothermic

Question 19

What are the industrial conditions for the haber process?

Answer 19

• 200 atmospheres of pressure
• 450 degrees centigrade
• Iron catalyst

Question 20

What are the raw materials for the have process?

Answer 20

Hydrogen - obtained by reacting natural gas (methane) with steam, or through the cracking of oil

Nitrogen - Obtained by burning hydrogen in air

Question 21

How is nitrogen obtained?

Answer 21

Air is 78% nitrogen nearly all the rest is oxygen. When hydrogen is burned in air the oxygen combines with hydrogen, leaving nitrogen behind.