Topic 2 - Materials From The Earth

Question 0

What are the two types of igneous rocks called and what are their properties? Give examples.

Answer 0

• extrusive igneous rocks - cool quickly above ground forming small crystals, e.g. Basalt and rhyolite.
• intrusive igneous rocks - cool slowly underground forming large crystals, e.g. Graphite and gabbro.

Question 1

How are igneous rocks formed?

Answer 1

• formed when molten magma pushes up into the crust before cooling and solidifying.
• contain various minerals in randomly arranged interlocking crystals.

Question 2

How are sedimentary rocks formed?

Answer 2

• formed from layers of sediment down in lakes or seas. Over millions of years the layers get buried under more layers and the weight pressing down squeezes out the water. Fluids flowing through the pores deposit natural mineral cement.

Question 3

What type of rock are chalk and limestone?

Answer 3

Sedimentary rocks and they contain fossils. The rock isn’t formed at high temperatures so remains and imprints of dead organisms aren’t destroyed. Limestone and chalk are easily broken away by wind, waves and rain, - this is called erosion.

Question 4

How are metamorphic rocks formed?

Answer 4

Formed by the action of heat and pressure of sedimentary rocks over long periods of time. The mineral and texture may have changed, but the chemical composition is often the same. So long as the rocks don’t melt, they’re metamorphic.

Question 5

How is marble formed?

Answer 5

Marble is formed from limestone or chalk. Very high temperatures break down the limestone and it reforms as small crystals. This gives marble a more even texture and makes it much harder.

Question 6

Limestone, marble and chalk are all made for the same chemical. Give it’s name and formula.

Answer 6

Calcium carbonate.
It’s found in the earths crust as marble, chalk or limestone.
The formula for it is CaCO3.

Question 7

Give 5 advantages of quarrying.

Answer 7

1) limestone provides things people want, e.g. Houses, paint, dyes and medicine. (Social)
2) limestone products are used to neutralise acidic soils. Also, acidity in lakes and rives caused by acid rain. (Environmental)
3) used in power station chimneys to neutralise sulphur dioxide, which is the cause of acid rain.
4) provides jobs for people and bring more money to the local economy. This can lead to local improvements in transport, roads, recreation facilities and health. (Social and economical)
5) once it’s complete, landscaping and restoration of the area is normally required as part of the planning permission. (Environmental and social).

Question 8

Give 5 disadvantages of quarrying.

Answer 8

1) makes huge holes which permanently damage and change landscape. (Environmental and social)
2) quarrying processes, like blasting rocks apart with explosives, make lots of noise and dust in quiet, scenic areas. (Social)
3) quarrying destroys the habitats of animals and birds. (Environmental)
4) limestone needs to be transported away, usually in lorries. Creates noise and pollution. (Social, economical and environmental)
5) waste materials cause unsightly tips. (Social and environmental).

Question 9

How is limestone made? What is it used for?

Answer 9

Formed from sea shells and although the original shells are mostly crushed,t here are still quote a few fossilised shells remaining.
Used for: blocks for buildings, statues, cathedrals, fancy carved bits on nice buildings, crushed into chipping and used in road surfacing.

Question 10

Describe the limestone cycle.

Answer 10

Calcium carbonate (limestone) –heat it
Calcium oxide (quicklime)–add water
Solid Calcium hydroxide (slaked lime) – add water
Calcium hydroxide solution (limewater) –add co2

Question 11

What is thermal decomposition?

Answer 11

It happens when one substance chemically changes into at least two new substances when it’s heated.

E.g. Calcium carbonate – calcium oxide + carbon dioxide

Question 12

How could you measure how easily a carbonate is decomposed?

Answer 12

Some carbonates undergo td more easily the others.
Less table carbonates decompose faster and limewater will turn cloudier faster.
Sometimes there is a colour change. E.g. Copper carbonate - green and copper oxide - black

Question 13

Describe the effect of water on calcium oxide.

Answer 13

When you add water to calcium oxide you get calcium hydroxide.

Question 14

Give two Uses for calcium oxide.

Answer 14

Can form a vigorous exothermic reaction when added to water, it forms calcium hydroxide. Can also neutralise acidic soils in fields when in powdered form.

Question 15

Give 2 uses for calcium hydroxide.

Answer 15

• soluble in water and dissolves to form limewater which is used to test for co2.
• can neutralise acidic soils in fields better than calcium oxide.

Question 16

Give 2 uses for calcium carbonate.

Answer 16

• can be used to remove acidic gases from coal-fired power station chimneys reducing harmful emissions and acid rain. Sulphur is passed through a mechanism that dissolve it to make an acid which is then neutralised by calcium carbonate by thermal decomposition.
• can be used to neutralise acidic soils in fields.

Question 17

Why do we need to treat emissions from coal fired power stations?

Answer 17

Coal contains sulphur and when this is burnt sulphur dioxide is produced which is a greenhouse gas and hugely damages our atmosphere.

Question 18

Define an atom.

Answer 18

The smallest particles you can get out of each element.

Question 19

Define an element.

Answer 19

A substance made from only one type of atom.

Question 20

Define a compound.

Answer 20

A substance made from two or more different elements chemically joined together.

Question 21

Define a molecule.

Answer 21

A group of two or more atoms that are joined together by chemical bonds.

Question 22

Explain conservation of mass.

Answer 22

During a chemical reaction, you have the same amount of atoms at the end which you had at the start. They’re just arranged differently to give a new product with different properties from the reactants.
The mass of the reactants equals the mass of the products. So if you react 6g mg with 4g O2 you’d have 10g MgO.
The total mass before and after a sealed reaction is unchanged.

Question 23

What’s a good way of demonstrating conservation of mass?

Answer 23

A precipitation reaction. A precipitation reaction happens she. Two solutions react and am insoluble forms in the solution. E.g.
Copper sulphate + sodium hydroxide — copper hydroxide + sodium sulphate.
Nothing has escaped from the flask, so the mass at the start and end of the reaction will be the same. No atoms gained or lost in the reaction, so mass gained or lost.