C2

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  • Created by: dkoning00
  • Created on: 23-05-16 18:41
What are the five layers of the Earth's structure, what are they made of and what are their depths?
Crust - solid rock, average depth 20km. Lithosphere (upper mantle and crust) - made up of tectonic plates, cold rigid rock, roughly 100km thick. Outer core - core makes up half Earth's radius, liquid iron and rock. Inner core - solid iron.
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What causes the tectonic plates in the lithosphere to move?
Convection currents caused by heat rising from the core as a result of radioactive decay
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Why do tectonic plate float on the mantle?
Because they're less dense than the mantle
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What is the difference between continental and oceanic plates?
Oceanic plates are thinner but more dense
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At roughly what speed do most tectonic plates move?
2.5cm per year
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What causes volcanoes and Earthquakes?
Plates moving against each other at boundaries
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Why is it difficult to study the inner structure of the Earth?
Because the crust is too thick to drill through and there is no drill in existence that is long enough and strong enough to get past it
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How is the Earth's structure studied?
Scientists use seismic waves and seismographs
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What are the two types of seismic waves? Describe them
P-waves (push, primary) - longitudinal fast travelling waves. S-waves (secondary) - transverse slower waves
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Which waves cannot travel through liquid?
S-waves
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How was this information used to prove the outer core is liquid?
S-waves couldn't be detected in the core's shadow (opposite epicentre) but P-waves could, proving they passed through liquid
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Who was the first scientist to suggest continental drift?
Alfred Weneger
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Briefly describe his theory
Millions of years ago there was one supercontinent (pangaea) which ad broken up and the pieces drifted apart to form our modern day continents
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What evidence suggested that Wegener was right?
Fossils found on each side of the Atlantic, similar rock layers, coast lines matching
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Why was his theory not accepted initially?
It contradicted the 'land bridge' theory and he couldn't explain how the plates moved
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How was Wegener's theory supported and accepted?
Studies of the mid-Atlantic ridge showed the plates moved apart to create a new sea floor. Also, the polarity of the rock changed symmetrically showing rock production over millions of years at a steady rate
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What causes volcanic eruptions?
Magma rises up to the crust and is released as lava under high pressure out of volcanoes
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What is subduction?
Oceanic plates are denser than continental plates. When they meet the oceanic plate is pushed down into the mantle and starts to melt. The magma created by the rock melting in the mantle rises up to form a volcano, eventually causing an eruption
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What is igneous rock?
Rock created when molten rock cools and solidifies
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What does the type of igneous rock formed depend on?
The makeup of the molten rock which affects the size of the rock crystals
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What does Extrusive cooling mean and cause?
Ingeous rock formed by magma cooling above ground. This means it cools quickly so the crystals don't have time to grow large.
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Give an example of an Extrusive igneous rock
Basalt, rhyolite, obsidian
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What does Intrusive cooling mean and cause?
Igenous rock formed when magma cools below the surface means it cools more slowly. This causes the crystals to be larger
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Give an example of an Intrusive igneous rock
Granite, gabbro, diorite
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Which type of lava is runny and flows?
Iron-rich basalt lava
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Which type is viscous and can be explosive?
Silica-rich rhyolite lava
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Why do geologists study volcanoes and their movements?
To better learn how they work in order to predict when they might erupt in the future
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What are the three types of rock?
Sedimentary, Igneous and Metamorphic
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How is sedimentary rock formed
Layers of sediment become compressed under each other and the pressure squeezes out the water which leaves behind mineral cement to form rock
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Give examples of sedimentary rocks
Sandstone, Limestone, Chalk
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How is limestone formed and what happens when it is heated?
Crushed seashells are compressed into rock on the sea floor. Thermal decomposition takes place turning calcium carbonate into calcium oxide and CO2
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How are metamorphic rocks formed?
By the action of extreme heat and pressure on below surface sedimentary and igneous rock
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Give examples of metamorphic rock and the rocks they come from
Marble - limestone, slate - shale, gneiss - granite
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What are ores? Give examples
Minerals we can get useful materials from
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How is glass made?
Melting limestone, sand and soda together
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Why is clay a good building material?
Because it is malleable when dug up making it easy to form into bricks etc. but it becomes very hard when heated
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What does clay contain?
Aluminium and silicates
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How is cement made?
Powdered clay and powdered limestone are roasted together to make a mixture of calcium and aluminium silicates
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How can cement be used to make concrete and why is this done?
By adding water and sand or gravel to give it higher tensile strength when it dries
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What is a composite material?
A composition of two or more materials to get better qualities like improved strength or lower density
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What is reinforced concrete?
A composite material - concrete set with steel rods to combine the hardness of concrete with the strength and flexibility of steel
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How can extracting rocks cause different environmental pollution?
Quarrying destroys habitats; transporting rock causes noise and air pollution; Quarrying produces dust and noise from dynamite; Disused sites can be dangerous e.g. people falling into quarries
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What electrolyte is used in the electrolysis of copper?
Copper (II) Sulphate
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What ions does it contain?
Cu2+
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What two electrodes are involved in electrolysis and what are their charges?
Anode - positive and Cathode - negative
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Describe the electrolysis to get pure copper?
Electrical current pulls electrons off of copper atoms at impure positive anode; Cu2+ ions are put into the solution from the anode; they are rejoined with electrons at the negative cathode from the electrical supply to make pure copper
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What reaction happens at the cathode?
Cu2+ (aq) + 2e- ---> Cu (s)
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What reaction happens at the anode?
Cu (s) ---> Cu2+ (aq) + 2e-
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What is reduction and where does it happen in the process?
Gain of electrons at the cathode
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What is oxidation and where does in happen in the process?
Loss of electrons at the anode
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Why is copper recycled instead of more being mined?
It is cheaper, only 15% of the energy needed to mine copper is used to recycle it, less pollution results
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What is an alloy?
A mixture of a metal and another element (can be metal or non-metal)
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Give examples of alloys and the metals/elements they contain
Brass (copper & zinc), bronze (copper & tin), steel (iron & carbon), solder (tin & lead), amalgam (mercury, silver, tin & copper)
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Why are alloys used?
Because they can combine properties of different elements to give useful materials that are better than its products alone
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Roughly how much carbon is usually in steel?
Less than 1%
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What are some of the advantages of steel over iron?
Steel is harder, stronger and less likely to rust (corrode)
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Give examples of common uses of steel
Girders, car parts, saucepans, cutlery
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Give advantages of brass and uses
Harder than copper or zinc, used for musical instruments, fixtures, fittings, doorknobs
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Give advantages of bronze and uses
Harder and stronger than copper or tin and has better corrosion resistance, used in springs, bearings, bells and sculptures
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Give advantages of solder and uses
Lower melting point than lead and tin, use for connecting circuits
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Give advantages of amalgam and uses
Hard wearing, used for fillings
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What are smart alloys?
Alloys that have been developed to have special useful properties
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What are Nitinols?
Alloys of nickel and titanium that have shape memory
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What is shape memory and how is it useful?
Alloys can be bent or twisted but return to their original shape under certain conditions (e.g. if heated). Used for frames for glasses
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What two conditions must be met for iron to corrode?
Must be in contact with water and oxygen
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Describe the process by which iron corrodes
Iron undergoes oxidation and gains oxygen to form Iron(III) Oxide. When this comes into contact with water it forms Hydrated Iron(III) Oxide which is commonly known as rust
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Give the word equation for this process
Iron + Oxygen + Water ---> Hydrated Iron(III) Oxide
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Why do cars parked near the coast rust quickly?
Because salt water speed up the process
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Why doesn't aluminium corrode even though it's most reactive than iron?
A thin surface layer oxidises to form Aluminium Oxide which doesn't flake off so creates a protective layer over the aluminum
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Give advantages and disadvantages of using aluminium in car bodies over steel
Ad: much lower density so increases fuel economy and bodies corrode less and have longer lifespan. Dis: It costs a lot more
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Give uses and reasons of materials used for building cars
Steel - body work, strong can be welded. Aluminium - engine parts, strong and low density. Glass - windows and windscreens, transparent and colourless. Plastics - insulators and interior, hard-wearing and lightweight. Fibres - seats and floors
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Why are car parts recycled and what are some of the problems with it?
To save natural resources and money and reduce landfill - plastics must all be separated before recycling
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What is an indicator?
A dye that changes colour depending on pH
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Give examples of substances with pH 1-6 (acid)
1 - car battery acid. 2 - stomach acid. 3 - vinegar/lemon juice. 4 - acid rain. 5 - normal rain. 6 - impure water
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Give examples of substance with pH 8-14 (alkaline)
8 & 9 - washing up liquid. 10 - pancreatic juice. 11 - soap powder. 12 & 13 - alkaline batteries. 14 - caustic soda (drain cleaner)
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Define an acid
A substance with a pH of less than 7 that form H+ ions in water - the concentration of which determine the strength of the acid.
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Define a base/alkali
A base is a substance with a pH greater than 7. An alkali is a base that is soluble in water and forms OH- ions in water - again the concentration determines the strength
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Give the word equation for a neutralisation reaction
Acid + Base ---> Salt + Water
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Give the ionic equation
H+ + OH- (reversible) H2O
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Metal oxides and metal hydroxides are...
Bases
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What does the neutralisation of hydrochloric acid and copper oxide produce?
Copper chloride + water
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Give the balanced symbol equation for this
2HCl + CuO ---> CuCl2 + H2O
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What does the reaction between an acid and a carbonate produce?
Salt, water and carbon dioxide
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What is produced by the reaction between hydrochloric acid and sodium carbonate?
Sodium chloride, water and carbon dioxide
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Give the balanced symbol equation
2HCl + Na2CO3 ---> 2NaCl + H2O + CO2
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What do reactions between acids and ammonia produce?
Ammonium salts
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Hydrochloric acid and Ammonia produces... Give the display formula
Ammonium chloride NH4Cl
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Sulfuric acid and Ammonia produces... Give the display formula
Ammonium sulfate (NH4)2SO4
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Nitric acid and Ammonia produces... Give the display formula
Ammonium nitrate NH4NO3
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What are fertilisers and why are they used?
Substances that provide plants with essential growth elements - used to increase crop yield in farming
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What are the three main essential elements in fertilisers?
Nitrogen, phosphorous and potassium
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Why are Ammonia Salts good fertilisers?
Because they contain many/all of the essential elements
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What acid neutralises Ammonia to make Ammonium Nitrate?
Nitric acid
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And Ammonium Phosphate?
Phosphoric acid
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What acid and base neutralise to make Potassium Nitrate?
Nitric acid and Potassium Hydroxide
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What environmental issues can be caused by over use of fertilisers?
Eutrophication
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Briefly describe eutrophication
Excess fertiliser on fields runs off into lakes and rivers; algae growth thrives due to nitrates and phosphates; Algae bloom blocks out light so water plants die; Aerobic bacteria use up oxygen; fish and other animals die due to low oxygen
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By what process would you make Ammonium Nitrate in a lab?
Titration
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Describe this process
Put an amount of Ammonia in a conicle flask with an indicator (UI, methyl orange etc.). Fill a burette with nitric acid. Slowly ad the acid until the indicator tells you the solution is neutral. You now have Ammonium Nitrate solution
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How could you obtain pure Ammonium nitrate crystals?
Neutralise Ammonia solution with nitric acid by titration and measure exactly how much acid is needed using the burette and indicator. Then mix the same amounts of each wihtout indicator. Put solution in a dish to gain crystals by evapouration
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Define yield
The mass of product created by a reaction
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By what process can Ammonia be obtained?
The Haber Process
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Give the balanced symbol equation for the Haber process
N2 + 3H2 2NH3
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What industrial conditions are required?
200 atmospheres of pressure, 450 dC and an Iron catalyst
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Why are these conditions used?
High pressure favours forwards reaction, high temperature favours reverse but also increases reaction rates so 450 dC is a compromise. Iron catalyst speeds up reaction
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Why is unreacted hydrogen and nitrogen recycled?
To reduce waste and save money
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What are the five factors that affect production costs in industrial processes?
Price of energy, cost of raw materials, labour costs, plant and equipment costs and rate of production
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Define optimum conditions
Conditions that give the lowest production costs for percentage yield and rate of reaction
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Give the display formula and chemical name for salt
NaCl - Sodium Chloride
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In what two ways can salt be extracted from the ground?
Drilling and mining rock salt or pumping hot water around underground to dissolve the salt in it - this is called solution mining
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What issues can mining salt cause?
If the underground cavities are not filled they can collapse causing subsidence on the surface
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What can salt be used for?
Flavour and preservative in food, making chemicals and melting ice on roads
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What does the electrolysis of brine produce and where?
Hydrogen gas at the negative cathode, Chlorine gas at the positive anode and Sodium Hydroxide formed from ions in the solution
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What four ions are involved?
Na+ OH- Cl- H+
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Describe the reaction at the cathode and give the balanced ionic equation
Two hydrogen ions (H+) accept one electron each to become a single hydrogen molecule (reduction) so H2 gas is given off: 2H+ + 2e- ---> H2
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Describe the reaction at the anode and give the balanced ionic equation
Two chloride ions (Cl-) lose one electron each to become a single chlorine molecule (oxidation) so chlorine gas is given off: 2Cl- - 2e- ---> Cl2
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What industry uses this process?
Chlor-alkali
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What are the products used for?
Hydrogen gas - used in Haber process. Chlorine - used for disinfectants, plastics, solvents and hydrochloric acid. Sodium hydroxide - used to make soap and can be reacted with chlorine to make bleach
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Card 2

Front

What causes the tectonic plates in the lithosphere to move?

Back

Convection currents caused by heat rising from the core as a result of radioactive decay

Card 3

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Why do tectonic plate float on the mantle?

Back

Preview of the front of card 3

Card 4

Front

What is the difference between continental and oceanic plates?

Back

Preview of the front of card 4

Card 5

Front

At roughly what speed do most tectonic plates move?

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