Using Resources

Question 1

Humans use the Earth’s natural resources for a number of purposes, including:

Answer 1

energy and fuels for warmth
building materials for shelter
food through farming
fuels for transport
materials for clothing

Question 2

Finite resources

Answer 2

Resource that can only be used once and is in limited supply. For example, oil is a finite resource.

Question 3

Renewable resources

Answer 3

Resources which will not run out in the foreseeable future. This could be because the reserves of the resources is huge, or because the current rate of extraction is low.

Question 4

For water to be potable, it must have sufficiently low levels of dissolved salts and microbes. This is because:

Answer 4

dissolved salts can sometimes be harmful for humans

microbes can cause illnesses`

Question 5

potable

Answer 5

Water that is safe to drink.

Question 6

What is a life cycle assessment ?

Answer 6

A life-cycle assessment or LCA is a ‘cradle to grave’ analysis of the impact of a manufactured product on the environment.

Question 7

What does and LCA include at all stages ?

Answer 7

At all stages, an LCA is likely to include information about the use of energy, transport of materials and the release of waste substances into the environment.

Question 8

What are the 4 stages of LCA ?

Answer 8

1) Raw materials
2) Manufacture
3) Use
4) Disposal

Question 9

What happens at the manufacture stage ?

Answer 9

The manufacture of products has an impact on the environment, including:

• using up land for factories
• the use of machines and people

Question 10

What happens at the use stage ?

Answer 10

The impact of a product on the environment during its use depends on the type product. For example, a wooden chair has very little impact, unless it needs cleaning or repair. On the other hand, using a car will have a significant impact.

Question 11

What happens at the disposal stage ?

Answer 11

The disposal of old products has an impact on the environment, including:

• using up land for landfill sites
• whether any or all of the product can be recycled or
  reused

Question 12

What happens at the raw materials stage ?

Answer 12

All the raw materials we need come from the Earth’s crust, atmosphere or oceans, or are due to living organisms. Obtaining these materials has an impact on the environment, including:

using up limited resources such as ores and crude oil
damaging habitats through quarrying, mining, or felling trees

Question 13

Recycling

Answer 13

Reusing materials or reprocessing waste materials to produce new materials.

Question 14

Advantages of recycling

Answer 14

• fewer quarries and mines are needed to extract finite
  reserves of metal ores
  -less crude oil needs to be extracted from the crust as
  a raw material for making plastics
  -less energy is needed for recycling compared with
  making a new product from natural resources, so the - - emission of greenhouse gases is reduced
  the amount of waste that is disposed of in landfill is
  reduced

Question 15

Disadvantages of recycling

Answer 15

• the collection and transport of used items needs organisation, workers, vehicles and fuel
• it can be difficult to sort different metals from one another
• the sorted metal may need to be transported to where it can be turned into ingots

Question 16

Phytoextraction

Answer 16

• plants are grown on a low-grade ore
• the plants absorb metal ions through their roots and
  concentrate these ions in their cells
• the plants are harvested and burnt
• the ash left behind contains metal compounds

Question 17

Phytoextraction is slow but it:

Answer 17

• reduces the need to obtain new ore by mining
• conserves limited supplies of high-grade ores
• reduces the amount of rock waste that must be
  disposed of after traditional mining

Question 18

Name and advantage and disadvantage of bioleaching…

Answer 18

Bioleaching does not need high temperatures but it produces toxic substances, including sulfuric acid, which damage the environment

Question 19

Bioleaching

Answer 19

Using bacteria to extract metals from their ores.

Question 20

WATER LEARN

Answer 20

WATER LEARN

Question 21

In the Haber process:

Answer 21

• nitrogen (extracted from the air) and hydrogen (obtained from natural gas) are pumped through pipes
• the pressure of the mixture of gases is increased to
  200 atmospheres
• the pressurised gases are heated to 450°C and
  passed through a tank containing an iron catalyst
• the reaction mixture is cooled so that ammonia -
  liquefies and can be removed
• unreacted nitrogen and hydrogen are recycled
• it is reversible !

Question 22

What are fertilisers ?

Answer 22

Fertilisers provide mineral ions needed for healthy growth in plants. As plants grow, they absorb mineral ions from the water in the soil through their root hair cells. Over time, the concentration of these ions decreases, so farmers and gardeners add fertilisers to the soil.

Question 23

What do fertilisers contain for them to increase growth ?

Answer 23

Fertilisers are formulations which may contain nitrogen, phosphorus and potassium compounds to promote plant growth.

Question 24

The importance of ammonia in making fertilisers

Answer 24

…..

Question 25

The reaction conditions in the Haber process are:

Answer 25

a temperature of 450°C
a pressure of 200 atmospheres
an iron catalyst

Question 26

How to make ammonia….

Answer 26

….

Question 27

Effect of increasing pressure on the Haber process

Answer 27

In a reaction involving gases as reactants and/or products, increasing the pressure of the reaction mixture will cause the equilibrium position to move to the side with the fewest moles of gas, to reduce the pressure.

There are fewer molecules on the right-hand side of the equation for the Haber process:

N2(g) + 3H2(g) ⇌ 2NH3(g)

1 + 3 = 4 molecules ⇌ 2 molecules

If the pressure is increased, the equilibrium position moves to the right, so the yield of ammonia increases. The rate of reaction also increases because the gas molecules are closer together, so successful collisions are more frequent.

However, the energy costs increase when higher pressures are used and the equipment becomes more expensive. Therefore, the choice of pressure is a compromise between yield and cost.

Question 28

Effect of temperature on the Haber process

Answer 28

When the temperature is increased, the position of equilibrium moves in the endothermic direction to reduce the temperature.

In the Haber process, the forwards reaction is exothermic, so the reverse reaction is endothermic.

N2(g) + 3H2(g) ⇌ 2NH3(g) (forwards reaction is exothermic)

This means that as the temperature is increased, the position of equilibrium moves to the left, and the yield of ammonia decreases.

It may seem sensible to use a very low temperature in order to maximise the yield of ammonia but lower temperatures reduce the rate of reaction. The temperature chosen is a compromise between yield and rate.

Question 29

Using a catalyst in the Haber process

Answer 29

A catalyst speeds up the rate of the forward and reverse reactions equally. This reduces the time taken for the system to reach equilibrium but it does not affect the position of equilibrium or the yield of ammonia.

Using a catalyst in the Haber process means that a lower temperature can be used whilst keeping the rate of reaction high. A lower temperature helps to keep the yield high.

Question 30

Reducing costs in other ways

Answer 30

Most of the hydrogen and nitrogen which go into the reactor leave unreacted. By recycling them back into the reactor, the cost of making the reactants from raw materials is reduced.