C2 (1) Flashcards
What is the Crust?
A thin outer layer of solid rock
What is the Lithosphere? Properties?
Includes crust and upper part of mantle.
Made up of tectonic plates
Relatively cold and rigid
What is the mantle?
Near the crust = rigid
Deeper = flow slowly and less rigid and temp. increases
What is the core?
Inner core = solid
Outer core = liquid
What does radioactive decay cause in the mantle?
Convection currents which causes plates to move
What are tectonic plates?
Float on mantle
Move 2.5cm per year
Volcanoes and earthquakes often occur where plates meet
What are used to study the structure of the Earth?
Seismic waves
What are seismic waves used for?
To study the structure of the earth
How are seismic waves used to study the earth?
Measuring the time takes for waves to travel through earth and where they’re detected.
P?waves = through liquid and solid
S?waves = only in solids
What causes seismic waves?
Earthquakes or man made explosions on earth’s surface
What is Wegener’s theory? (1914)
Said that Africa and South America had previously been one continent that had split.
Continental drift” that there was once one supercontinent that has drifted apart.”
What evidence supported Wegener’s theory?
Matching rock layers on the different continents.
Same earthworms
Why wasn’t Wegener’s theory accepted at first?
The movement wasn’t detectable and the drifting” explanation wasn’t convincing.”
What new evidence was found in 1960? (Sea floor spreading)
Scientists investigated mid?atlantic ridge.
Evidence that magma rises up through sea floor, solidifies and forms underwater mountains that are roughly symmetrical either side of the ridge. (Suggests that sea floor is spreading)
What new evidence was found in 1960? (Rocks)
The magnetic oritentation of rocks.
As magma erupts through gap, iron particles in rocks align with magnetic field. The magnetic field swaps direction and rock either side of the ridge has bands of magnetic polarity.
What causes volcanoes to occur?
When molten rock (magma) from the mantle emerges through the Earth’s crust
What is subduction?
When a dense oceanic plate is forced under a less dense continental plate
How do oceanic and continental plates colliding cause volcanoes?
The oceanic plate is forced under continental
Oceanic plate is cooler at edges so they sink easily, pulling the plate down
As it is forced down the oceanic crust melts and starts to rise.
If the molten rock comes to the surface = volcano
What rocks are made from molten rock cooling down and solidifying?
Igneous rocks
What does the type of igneous rock made depend on?
How quickly the magma cools
The composition of the magma
When is an eruption fairly safe?
If the magma forms iron?rich basalt and the lava from the eruption is runny
When is an eruption explosive?
If the magma is silica?rich rhyolite. Thick lava is produced which can be violently blown out the volcano
Why is it hard to predict the eruptions of volcanoes?
They are very unpredictable
Scientists can only say more than normal to happen not that its certain
How are sedimentary rocks formed?
?Formed from layers of sediment in lakes or seas
?Over millions of years layers get buried under more layers ad the weight of this squeezes the water out
?Fluids flowing through the pores deposit natural mineral cement
What is limestone formed from?
Seashells = calcium carbonate
What is produced when limestone (CaCO3) thermally decomposes?
Calcium oxide and carbon dioxide
CaCO(3) = Ca0 + C0(2)
How are metamorphic rocks formed?
By the action of heat and pressure on sedimentary or igneous rocks over long periods of time
Eg. Marble formed from limestone
How are igneous rocks formed?
When magma cools
Why are igneous rocks very hard?
Contain various mineral in randomly arranged interlocking crystals = very hard
Eg. Granite
Where do we get/find aluminium and iron from?
Extracting from ores in rocks
How is glass made?
Heating limestone, sand and soda until it melts =glass
How are bricks made?
By firing clay at very high temperatures
How is cement made?
By roasting powdered clay and powdered limestone in a kiln to make a complex mixure of calcium and aluminium silicates
What happens when cement is mixed with water?
Slow chemical reaction takes place
Causes cement to gradually set hard
What can cement be mixed with to make concrete?
Sand, aggregate and water
What are two advantages for using concrete to construct buildings?
Cheap and very quick
What is reinforced concrete?
Composite material
Combination of concrete and steel
What is the advantage of reinforced concrete?
Combines the hardness of concrete with the flexibility and strength of steel
What four environmental problems are linked to extracting rocks?
- Quarrying uses up land
- Transporting rocks = noise and pollution
- Quarrying process produces dust and noise
- Disused sites are dangerous.
? Former quarries = people drown
? Former mines = collapse
What is an alloy?
A mixture of a metal and other elements
Eg. Two or more different metals
Metal and a non?metal
Why are alloys often more useful than the pure metal?
Because new properties are made and these are often more useful than the pure metals properties
What is steel an alloy of?
Iron and carbon
What properties does steel have due to being an alloy?
Harder than iron
Stronger than iron
Iron corrodes, steel doesn’t
What are some uses of steel?
Bridges, engine parts, cutlery, cars and ships
What is brass an alloy of?
Zinc and copper
What are the properties of brass?
Mixture of those of copper and zinc
Brass is harder than either of them
What uses does brass have?
Muscle instruments and screws
What is bronze an alloy of?
Copper and tin
What properties does bronze have?
Stronger and harder than tin
More resistant to corrosion
What uses does bronze have?
Springs, motor bearings, sculptures and bells
What is solder an alloy of?
Lead and tin
What does the alloy amalgam contain?
Mercury
Often used in dentistry
What is an example of a smart alloy?
Nitinol = alloy of nickel and titanium
What property does nitinol have?
Shape memory = goes back to being original shape after being bent and twisted
What is nitinol often used in?
Glasses frames
What is the word equation for the corrosion/rusting of iron?
Iron + Oxygen + Water = Hydrated iron (III) oxide
Why doesn’t aluminium corrode when wet?
Aluminium reacts quickly with oxygen and forms aluminium oxide.
This acts as a protective layer to stop any further reaction take place
What are two reasons for why car bodies are often made out of aluminium rather than steel?
- Lower density = lighter = better fuel economy = saves fuel resources
- Corrodes less = longer lifetime
What is a major disadvantage of aluminium?
Costs a lot more than iron or steel
What five different materials are needed to build different bits of a car?
- Steel: Bodywork
- Aluminium: Engine parts
- Glass: Windscreens/windows
- Plastics: Internal coverings
- Fibres: Seats and floorings
What are three reasons for why cars are recycled?
Save natural resources
Save money
Reduce landfill use
What is an acid?
A substance with a pH less than 7.
What do acids form in water?
H+ ions
How is the pH of an acid determined?
The concentration of H+ ions
What is a base?
A substance with a pH greater than 7.
what do bases form in water?
OH? ions
What is an alkali?
A base that is soluble in water
What is the reaction between acids and bases called?
Neutralisation
What is the word equation for neutralisation?
Acid + Base = Salt + Water
What is the equation for neutralisation in terms of H+ and 0H? ions
H+ + 0H? = H(2)0
This is a reversible reaction
C2
C2
