Topic 4

Question 1

How can metals reacting with acids tell you about their reactivity? (HCl)

Answer 1

1. The more reactive a metal is, the faster the reaction will be (the speed can be seen by the rate at which bubbles of hydrogen are formed)
2. Very reactive metals will fizz vigorously

Question 2

What will happen to reactive metals in water?

Answer 2

They would react vigorously

Question 3

What is the reaction that takes place (word equation) between reactive metals and water?

Answer 3

metal + water = metal hydroxide + hydrogen

Question 4

How can you test that hydrogen is present in a reaction

Answer 4

Through the burning splint. The louder the sqeaky pop, the more hydrogen has been made and the more reactive a metal is

Question 5

What type of reaction are displacement reactions?

Answer 5

Redox reactions

Question 6

What are the two definitions of oxidation/reduction?

Answer 6

1. Oxidation/reduction could refer to the loss and gain of oxygen
2. . Oxidation and reduction could refer to the loss and gain of electrons

Question 7

What happens in a displacement reaction and what does this mean in terms of oxidation and reduction?

Answer 7

A more reactive element reacts to take the place of a less reactive element in a compound. Therefore, the more reactive element is oxidised and the less reactive element is reduced

Question 8

What determines how reactive a metal is?

Answer 8

How easily the metal can lose electrons to form cations

Question 9

Combustion reactions involved…(oxidation/reduction/both)? and they’re always…. (exothermic/endothermic?)

Answer 9

1. Oxidation

2. Exothermic

Question 10

What is an ore?

Answer 10

A rock that contains enough metal to make it economically worthwhile extracting the metal from it

Question 11

The extraction of metals involves …… oxidation of ores/reduction of ores?

Answer 11

reduction of ores

Question 12

Outline the two main ways of extracting metals

Answer 12

1. Carbon reduction

2. electrolysis

Question 13

When can carbon reduction take place?

Answer 13

The metal must be below carbon in the reactivity series

Question 14

What is a disadvantage of electrolysis as opposed to carbon reduction?

Answer 14

Electrolysis is more expensive as it requires a large amount of energy (electricity) and the costs for melting or dissolving the metal ore is high

Question 15

How does bioleaching works? (to extract metals)

Answer 15

This uses bacteria to separate metals from their ores. The bacteria get energy from the bonds between the atoms in the ore, separating out the metal from the ore in the process. The leachate (solution produced by process) contains metal ions that can be extracted by electrolysis/displacement reactions

Question 16

How does phytoextraction work?

Answer 16

This involves growing plants in soil that contains metal compounds. The plants can’t use or get rid of the metals so they gradually build up in the leaves. The plants can be harvested, dried or and burned in a furnace. The ash contains metal compounds from which the metal can be extracted by electrolysis/displacement reactions

Question 17

Metals higher up in the reactivity series are the ….(most/least) resistant to oxidation

Answer 17

least

Question 18

What are the advantages of recycling?

Answer 18

• Conserves resources and energy
• Protects the environment
• Has economic benefits (extracting materials costs money)

Question 19

Outline the 4 stages in a life cycle assessment?

Answer 19

1- Choice of material
2- Manufacture
3- Product use
4- Disposal

Question 20

Describe the ‘choice of material’ stage of a LCA?

Answer 20

1- metals have to be mined and extracted from ores, which requires energy and can cause pollution
2- Raw materials from chemical manufacture often come from crude oil, which is non renewable

Question 21

Describe the manufacture stage of a LCA?

Answer 21

1- manufacturing products use energy, can cause pollutions and produce waste products that need to be disposed of (recycling?)
2- Most manufacture needs water, business need to make sure they dont put polluted water back into environment

Question 22

Describe the ‘product use’ stage of a LCA?

Answer 22

Using a product can damage the environment as:

1- paint e.g. gives off toxic fumes
2- Burning fuels releases greenhouse gases and other harmful substances
3- Fertiilisers can leach into streams and damage ecosystems

Question 23

Describe the disposal stage of a LCA?

Answer 23

1- Products are often disposed off in a landfill. This takes up space and can pollute land and water
2- Products might be incinerated (burnt), which causes air pollution

Question 24

What is a reversible reaction?

Answer 24

A reaction where the products can react with each other to produce the original reactants.

Question 25

What type of reaction is the Haber Process?

Answer 25

A reversible reaction

Question 26

What two elements react to form ammonia and what temperature and pressure is haber process carried out at?

Answer 26

Nitrogen and Hydrogen - 400 degrees celsius and 200 atmospheres

Question 27

How does changes in temp affect equilibrium?

Answer 27

1) If you decrease the temp, the equilibrium will move in the exothermic direction to produce more heat 2) If you increase the temp, equilibrium will move in the endothermic direction to absorb extra heat

Question 28

How does changes in pressure affect equilibrium?

Answer 28

1) If you increase pressure, equilibrium will move towards the side that has fewer moles of gas to reduce pressure 2) If you decrease pressure, equilbrium will move towards the side that has more moles of gas to increase pressure

Question 29

How does changes in conc affect equilibrium?

Answer 29

1) If you increase the conc of the reactants, the equilibrium will move to the right to use up the reactants (making more products) 2) If you increase the conc of the products, equilbrium will move to the left to use up the products (making more reactants) 3) Decreasing the conc will have the opposite effect

Question 30

What happens at dynamic equilibrium?

Answer 30

- As reactants react, their concs fall so the forward reaction slows down. But as more products are being made and their concs rise, the backwards reaction speeds up until the forward reaction will be going at exactly the same rate and same time as the backwards one (no overall effect) - The concs of reactants/products reach a balance at dynamic equilibrium and wont change

Question 31

What three things can change the position of equilbrium?

Answer 31

1- Temperature 2- Pressure 3- concentrations

Question 32

What type of catalyst is used in the haber process?

Answer 32

Iron catalyst