Chemistry C2

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What is the lithosphere?
It is the outer layer of the earth and consists of the crust and the top part of the mantle.
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What is the lithosphere made from?
Tectonic plates that are less dense than the mantle below.
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Why is it hard to collect information about the construction of the earth?
Because the crust is too thick to drill through
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How is most of our information about the Earth collected?
Seismic waves produced by earthquakes and man-made explosions.
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Where is the mantle, and what are its properties?
It is the zone between the core and the crust. It is cold and rigid just below the crust, but at greater depths it is hot and non-rigid and able to move.
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Why does the temperature of the mantle increase with depth?
Because the Earth's core transfers energy.
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What current slowly moves plates?
Convection currents.
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How do we know that the oceanic crust is denser than the continental crust?
Because during subduction, the oceanic plate is pulled down.
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Describe the proccess of subduction
The oceanic crust is denser than the continental crust. When the plates collide, the oceanic plate sinks, pulling more of it down, and partly melting it as it reaches the hotter part of the mantle.
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What does the Plate tectonic theory suggest about Africa and South America?
That they may have once been one land mass.
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Why is the theory of Plate tectonics accepted more now?
Because it explains a wide range of evidence, and has been discussed and tested by many other scienctists.
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What theory did Wegener develop?
Continental drift theory (1914)
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What led to Wegener's theory becoming accepted?
Evidence of the sea floor spreading was found, and research was done that supported it.
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What causes volcanos?
When magma rises up through the Earth's crust because it is less dense than the crust.
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Why do Geologists study volcanos?
To try and predict future eruptions and to reveal more about the structure of the Earth.
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What type of rock is formed from lava?
Different types of igneous rock
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What comes from runny lava in slower eruptions?
Iron rich basalt rock
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What comes from thick lava in explosive eruptions?
Silica rich rhyolite
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What building material can these raw materials be made into? CLAY, LIMESTONE AND CLAY, SAND, IRON ORE, ALUMINIUM ORE.
Brick, cement, glass, iron, aluminium
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Where can some of these raw materials be found?
In the Earth's crust
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How can hardness be compared?
By rubbing the two materials together.
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Which is harder, marble or granite?
Granite
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Which is harder, marble or limestone?
Marble
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What type of rock is limestone, and how are they formed?
Limestone is a sedimentary rock, and is formed when soft sediments are compressed and cemented together.
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What type of rock is marble, and how are they formed?
Marble is a metamorphic rock, and is formed when limestone is changed by heat and pressure.
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What are metamorphic rocks typically composed of?
an interlocking mosaic of carbonate crystals.
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What type of rock is Granite, and how is it made?
Granite is an igneous rock, and is formed when magma cools and solidifies
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Why are igneous rocks so hard?
Because they are made with interlocking crystals
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What is thermal decomposition?
When one substance breaks down when heated to give at least two new substances.
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Calcium carbonate thermally decomposes. What is the word equation?
Calcium carbonate --> calcium oxide + carbon dioxide
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What is the symbol equation for the thermal decomposition of Calcium carbonate?
CaCO3 --> CaO + CO2
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How is cement made?
When limestone is heated with clay
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How is concrete made?
By mixing cement, sand and small stones with water
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What is a composite material?
It contains at least two materials that can still be distinguished.
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How is reinforced concrete a composite material?
It has steel rods running through the concrete.
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Concrete is strong under _______, but weak under _______.
Compression, tension
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How can impure copper be purified in a lab?
Using an electrolysis cell
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What are the advantages of recycling copper?
It has a fairly low melting point, so does not take much energy so cost is low, it reduces need for mining, stopping enviromental problems associated with mining, it keeps the cost of copper lower.
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What are the disadvantages and problems of recycling copper?
Small amounts used are difficult to seperate, valuble 'pure' copper must not be mixed with less pure scrap, less copper is mined so less mining jobs, the seperating process may produce pollution, a lot of copper is thrown away.
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What solution is used in the purification of copper?
Copper (II) sulfate solution
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What is the positive anode made from?
Impure copper
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What is the negative cathode made from?
A sheet of pure copper
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What happens to the mass of the anode and the cathode during electrolysis?
The anode loses mass as the copper dissolves, the cathode increases is mass as pure copper is deposited onto it.
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What is the electron half equation for oxidation at the anode?
Cu - 2e- --> Cu2+
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What is the electron half equation for reduction at the cathode?
Cu2+ + 2e- --> Cu
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What is an Alloy?
A mixture containing at least one metal
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What is the alloy Brass made from?
Copper and zinc
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What can happen to SOME smart alloys when heated to a specific temperature?
They return back to their original shape
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What is the alloy Nitinol used for and why?
It is used for spectacle frames because it returns to its original shape after being put in hot water.
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Why are smart alloys becoming more important?
Because new ways are being found to use them.
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Which two metals rust? What do all other metals do?
Iron and steel rust. All other metals corrode.
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What accelerates rusting?
acid rain and salt water.
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Why is rusting an oxidation reaction?
Because it reacts with oxygen to form an oxide
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What is the word equation for rusting?
Iron + water + oxygen --> Hydrated iron (III) oxide
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Why is aluminium used in car bodies and wheel hubs?
It does not corrode, low density, malleable, quite strong
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Why is copper used in electrical wires?
Good electrical conductore, ductile
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Why is lead used in lead acid batteries?
There is a chemical reaction with lead oxide that produces electricity.
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Why is plastic used in dashboards, dials and bumpers?
rigid, does not corrode, cheap
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Would you use steel or aluminium for a car body, give advantages and disadvantages for both.
Aluminium is lighter and more resistant to corrosion, but steel costs less and is stronger.
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What are the advantages of recycling materials from old cars?
Less mining saves finite resources, less crude oil is needed to make new plastics, less waste put in landfills, fewer toxic materials are dumped.
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What are the disadvantages of recycling materials from old cars?
Fewer mining jobs, difficult to seperate the materials, some seperating techniques produce pollution, some recycling processes are very expensive.
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What is made in the Haber process?
a nitrogen fertiliser called AMMONIA
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What is the word equation for the Haber process?
Nitrogen + Hydrogen Ammonia
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What is the balanced symbol equation for the haber process?
N2 + 3H2 2NH3
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What are the best conditions for the Haber process?
A catalyst made from iron, a temperature of about 450 degrees, a high presure of 200 atm, recycle any unused nitrogen and hydrogen.
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How does the iron catalyst make the process efficient?
It increases the rate of reaction, but NOT the percentage yield.
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How does high pressure make the process efficient?
It increases the percentage yield of Ammonia
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Why is the optimum temperature 450 degrees?
Although the yield is not high, the rate is fairly quick. Too high of a temperature would break down the ammonia, reducing the percentage yield.
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How does the Haber process help to reduce costs?
Uses a catalyst which is never used up, the materials that do not react are recycled, and automation is used, reducing wage bills
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What is the main aim of having optimum conditions?
To keep costs low
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What is an alkali?
A soluble base
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When does neutralisation take place?
When an acid and a base react to give a salt and water
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What is the word equation for neutralisation?
acid + base --> salt + water
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Why does universal indicator show a gradual change through a range of colours?
Because it is a mix of several different indicators
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How is the PH of an acid determined?
By the concentration of H+ ions. The higher the concentration the lower the PH
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What is the symbol reaction for neutralisation?
H+ + OH- H2O
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What are the two word equations for making salts?
acid + base -> salt + water AND acid + metal carbonate -> salt + water + carbon dioxide
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Why do farmers use fertilisers?
To increase crop yields
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Why do the fertilisers have to be dissolved in water before they can be absorbed by the plants?
Only dissolved substances are small enough to be absorbed
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Why are fertilisers needed?
Because the population is rising, so there is a higher demand for food.
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How do fertilisers increase crop yield?
They replace essential elements used by the previous crops, they also provide nitrogen that results in increased plant growth.
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What is eutrophication?
When fertilisers are washed into ponds, lakes and rivers, encouraging algae growth.
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How does eutrophication happen? (continued on next flashcard)
Fertilisers are washed off fields, increasing the nitrate and phosphate levels in the water. This encourages algae growth on the surface, known as algal bloom. The algae blocks sunglight so oxygen producing plants die,
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Cont.
The aerobic bacteria useup the little oxygen left and feed on the dead and decaying plants, meaning most organisms die.
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Why is it fairly easy to create a fertiliser?
Because most of them are salts, so an acid and an alkali can be reacted.
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Explain the process of making a fertiliser
The alkali is titrated into the acid using an indicator until it is completey neutral. It is repeated again without the indicator, and heated so most of the water evaporates. The remaining solution is left to crystalise, and is then filtered.
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Name the two ways salt is mined in Chesire
Mining from the ground as rock salt, and pumping in water and extracting the salt solution
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What chemical can be seperated by electrolysis?
Sodium chloride solution
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What is made at the negative cathode?
Hyrdogen
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What is made at the positive anode?
Chlorine
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What forms in the solution?
Sodium hydroxide
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Why is it important to use inert electrodes?
Because hydrogen and chlorine are reactive, so it is important that the electrodes do not dissolve or react.
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What is the formula for oxidation in the electrolysis of sodium chloride?
2Cl- - 2e- --> Cl2
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What is the formula for reduction in the electrolysis of sodium chloride?
2H+ + 2e- --> H2
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What two things are used to make household bleach?
sodium hydroxide and chlorine
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What else are they used to make?
Solvents, plastics, paints, soaps, medicines, food.
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Other cards in this set

Card 2

Front

Tectonic plates that are less dense than the mantle below.

Back

What is the lithosphere made from?

Card 3

Front

Because the crust is too thick to drill through

Back

Preview of the back of card 3

Card 4

Front

Seismic waves produced by earthquakes and man-made explosions.

Back

Preview of the back of card 4

Card 5

Front

It is the zone between the core and the crust. It is cold and rigid just below the crust, but at greater depths it is hot and non-rigid and able to move.

Back

Preview of the back of card 5
View more cards

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sufiya4771

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