Electrolysis, metals and equilibrium 1

Question 1

Reversible reactions

Answer 1

Products react to form reactants

Question 2

Where does dynamic equilibrium occur

Answer 2

In a closed system where there’s no loss of reactants or products

Question 3

Dynamic equilibrium

Answer 3

The forwards and backwards reaction are still occurring but percentages of reactants and products are no longer changing

Question 4

Why can’t dynamic equilibrium be achieved in an open system ?

Answer 4

Gases could escape and equilibrium can’t be achieved

Question 5

How to manufacture ammonia

Answer 5

By the Haber process
Involves the reversible reaction between nitrogen (from the air) and hydrogen from natural gas that can reach a dynamic equilibrium.

Question 6

What are the conditions in the haber process to favour the forward reaction?

Answer 6

450 degrees
Pressure of 200 atmospheres
Iron catalyst

Question 7

How can the equilibrium position be altered

Answer 7

By changing the concentration, pressure or temperature

Question 8

What does increasing temp do

Answer 8

Equilibrium position shifts in the endothermic direction

Transfers energy from the surroundings, cooling them down

Question 9

What does decreasing temp do

Answer 9

Equilibrium position shifts in the exothermic direction

Transferring energy to the surroundings heating them up

Question 10

Is the forward reaction endo or exothermic

So what’s the backwards reaction

Answer 10

Exothermic

Backwards is endothermic

Question 11

What does increasing and decreasing gas pressure do?

Answer 11

Increasing- equilibrium position shifts in the direction that forms fewer gas molecules as this reduces pressure.
Decreasing- equilibrium position shifts in the direction that forms more gas molecules as this increases pressure.

Question 12

What does increasing and decreasing a concentration do

Answer 12

Increasing- equilibrium position shifts in the direction that uses up the substance that’s been added.
Decreasing- equilibrium position shifts in the direction that forms more of the substance that’s been removed.

Question 13

What happens to copper in electrolysis of copper sulphate

Answer 13

Copper is less reactive than hydrogen so will be produced at the cathode (+ cathode gains mass)

Question 14

What is produced at the anode in electrolysis of copper sulphate

Answer 14

Oxygen and water

Question 15

What is produced at the cathode in electrolysis of copper sulphate

Answer 15

Copper

Question 16

What is usually used as an electrode and why

Answer 16

Platinum or graphite because they’re inert (unreactive)

Question 17

What’s the half equation for the cathode in electrolysis of copper sulphate

Answer 17

Cu2+2e- = (reduction)Cu

Copper ions are gaining 2 electrons to for copper atoms

Question 18

What’s the half equation for the anode in electrolysis of copper sulphate

Answer 18

4OH- = (oxidation)O2+2H2O + 4e-

4 hydroxide ions react to form oxygen gas and water losing 4 electrons.

Question 19

The metals that react with cold water form

Answer 19

Hydrogen and a metal hydroxide solution

Question 20

Metals that react with steam form

Answer 20

Hydrogen and a solid metal oxide

Question 21

The metals that react with dilute acids form…

And what will be seen

Answer 21

Hydrogen and a salt solution

Bubbles- more depending on the reactivity of the metal

Question 22

Advantages of recycling metals

Answer 22

Natural reserves of metal ores will last longer
Need to mine ores is reduced (reducing noise and pollution)
Less pollution (sulphur dioxide when sulphur is extracted from metal sulphide ore)
Less energy needed to recycle than to extract new metal
Less waste metal in landfill sites

Question 23

Disadvantages of recycling metals

Answer 23

Expensive to collect, transport and sort metals

Can use more energy than mining new ores

Question 24

Life cycle assessment stages

Answer 24

Obtaining and processing raw materials
Manufacturing and packaging products
Using product
Disposing of product

Question 25

What are cations and which electrode are they attracted to

Answer 25

Cations are positive ions and are attracted to the negative cathode

Question 26

What are anions and which electrode are they attracted to

Answer 26

Anions are negative ions and are attracted to the positive anode