Chemistry Paper 2

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  • Created by: lx1234
  • Created on: 06-03-18 22:56
How do you calculate empirical formulae?
1. Write symbol as a header, 2. Mass, 3. Write down Mr 4. Mass/Ar 5. divide answer by smallest. 5. Ratio.
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What are the physical properties of the alkali metals?
Good conductors of heat and electricity, Shiny when freshly cut, soft, relatively low melting points but are all solid.
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What is the word equation to show how Alkali Metals react with water?
Metal + Water ----> Metal Hydroxide + Hydrogen
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How does Lithium react with water?
Fizzes steadily.
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How does Sodium react with water?
Melts into a ball from the heat released in the reaction and fizzes rapidly
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How does Potassium react with water?
Gives off sparks and the hydrogen produced burns with a lilac coloured flame.
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What is the density as you go down the alkali metals?
Decreases as you go down.
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How many atoms are in the Halogens?
2
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How are the halogens bonded?
Covalently.
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What happens when you go down group 7?
Melting points increase, boiling points decrease.
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What happens to the intermolecular forces when a simple substances melt or boil?
Weak forces are overcome, whilst strong forces do not break.
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What happens to the intermolecular forces as you go down group 7?
They get stronger, more heat is needed to overcome the forces.
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What are the four main Halogens you need to know?
Fluorine, Chlorine, Bromine and Iodine
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What colour and state is Fluorine at at room temperature?
Gas, pale yellow
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What colour and state is Chlorine at at room temperature?
Gas, Yellow/green
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What colour and state is Bromine at at room temperature?
Liquid, Red/Brown
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What colour and state is Iodine at room temperature?
Solid, dark grey.
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What happens when a halogen reacts with a metal or a hydrogen?
Each halogen atom gains one electron to complete its outer shell.
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What is the word equation for halogens reacting with metals?
Halogen + Metal ----> Metal Halide (e.g Sodium Chloride)
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What charge do the Ions formed from the reaction of Halogens with Metals?
1-
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Why are noble gasses inert?
Full outer shell of electrons, so there is no tendency to lose, gain or share electrons
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Why is helium used to lift gasses, e.g in airships and party balloons?
Helium is less dense than air, and is non flammable so doesn't catch fire.
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Why is Argon, Krypton and Xenon used for filling gas in filament lamps?
The metal filament becomes hot enough to glow, the inert gasses stop it burning away
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Why is Argon used as a shield gas during wielding?
Argon is denser than air so it keeps air away from the metal, it is inert so the metal does not oxidise.
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What must happen for a reaction to take place?
Reacting particles must collide with each other and the collisions must have enough energy.
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How does Concentration and Pressure effect rate of reaction?
There are more particles in the same volume, so the particle collision frequency increases.
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How does Surface area:Volume ratio effect rate of reaction?
More particles of a reactant are available, so particle collision frequency increases
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How does temperature effect rate of reaction?
Particles move faster, particle collision frequency increases and energy of collision increases so a greater proportion of collisions are successful.
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What is activation energy?
The minimum energy needed by reactant particles for a reaction to happen
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What is an exothermic reaction?
Heat energy is given out to the surroundings and the reaction mixture or the surroundings increase in temperature
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What is an endothermic reaction?
Heat energy is taken in from the surroundings and the reaction mixture or the surroundings decrease in temperature
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Name reactions that can be either exothermic or endothermic
Neutralisation, displacement, precipitation and dissolving.
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Name a reaction that is always endothermic
Bonds being broken
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Name a reaction that is always exothermic
Bonds being made OR combustion
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What should you see on a reaction profile for exothermic reactions?
Energy level of the reactants is greater than energy level of products, energy change of the reaction is negative.
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What should you see on a reaction profile for endothermic reactions?
Energy level of reactants is lower than the energy level of the products, the energy change of the reaction is positive.
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What is a hydrocarbon?
Compounds consisting only of hydrogen and carbon
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What can hydrocarbons consist of?
Chains or rings of carbon atoms
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What is a crude oil?
A complex mixture of hydrocarbons with their carbon atoms in chains or rings, and important source of useful substances, a finite source.
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How does fractional distillation take place?
1. Oil is heated to evaporate it, 2. Vapours rise in fractionating column, hot at bottom, cool at top, 4. Each column condenses where it becomes cool enough and is piped out of the column.
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What is a fraction?
A mixture of hydrocarbons with similar boiling points and numbers of carbon atoms.
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What happens as the number of carbon and hydrogen atoms in a hydrocarbon molecule increases?
Strength of intermolecular forces increases, energy must be transferred to overcome these forces, boiling point increases
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Name a use for bitumen
Surfacing roads and roofs
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Name a use for gases
Domestic heating and cooking.
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Name a use for Kerosene
Fuel for aircraft
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What is an Alkane?
A homologous series of hydrocarbons
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What is a homologous series?
A series of compounds in which molecular formula of neighbouring members differs by CH2, that show gradual variation in physical properties and that have similar chemical properties.
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What are the chemical properties of Alkanes?
When they react completely with oxygen, carbon dioxide and water vapour form.
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What are the differences between Complete Combustion (CC) and Incomplete Combustion (IC)
CC= Hydrogen oxidised to water vapour, carbon oxidised to CO2, exothermic. IC= carbon may become carbon monoxide, soot and less energy is given out
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What is Acid Rain?
Sulfur Dioxide
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What are the effects of acid rain?
Rivers, lakes and soils are more acidic which harms organisms living in them, houses weather faster, trees are damaged.
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How does Acid Rain take place?
1. Waste gas from power stations contain sulfur dioxide. 2. Sulfur dioxide dissolves in water in the air. 3. Rain is more acidic than normal
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How can you reduce acid rain?
Removing sulfur from petrol, diesel and fuel at oil refinery before selling it, preventing sulfur dioxide leaving power stations and adding calcium carbonate or hydroxide to fields and lakes to neutralise excess acid from acid rain.
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What is the word equation for the reaction of Hydrogen with Oxygen
Hydrogen+Oxygen----->Water
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How is Hydrogen manufactures as a fuel?
Electrolysis of water, cracking of oil fractions, reaction of natural gas with steam.
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What are the benefits of Hydrogen Fuels?
Burns easily, does not produce ash or smoke, only produces water, three times as much energy produced as petrol.
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What are the disadvantages of Hydrogen fuels?
Hydrogen is a gas, so needs to be stored at high pressures, filling stations would have to be adapted to withstand high pressures.
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What is cracking?
Breaking down larger alkane into smaller, more useful alkanes and alkenes.
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How do you crack in a lab?
1. Porous pot catalyst is heated carefully. 2. Liquid parafin is heated and evaporated. 3. Paraffin vapour passes over hot porous pot, hydrocarbon molecules break down. 4. One product is ethene, collects in other tube as a gas.
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What do scientists believe about the Earths early atmosphere?
There was little or no oxygen, there was large amounts of carbon dioxide, water vapour and small amounts of other gasses
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What is evidence for the theory of lack of oxygen in Earths early atmosphere?
Banded Iron Formation rocks, or Stromatolite.
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How did the Earths atmosphere develop to increase oxygen?
1. Earth cools, oceans form. 2. Life evolves in oceans, photosynthesis begins. 2. Oxygen buildup in oceans. 3. Then atmosphere.
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How did the Earths atmosphere develop to decrease carbon dioxide?
1. Carbon dissolved in oceans. 2. Marine organisms used dissolved CO2 to make calcium carbonate for shells. 3. Shells of dead organisms become part of sediment. 4. Over millions of years, sediment layers squash, become sedimentary rocks.
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What is the greenhouse effect?
Greenhouse gasses in the atmosphere absorb heat radiated from the Earth, the gasses then release energy in all directions, reducing the amount of heat radiating into space, keeping Earth warm.
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What is global warming associated with?
Climate change and rising sea levels due to melting ice and expanding ocean water.
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What is global warming?
An increase of the warming effect in the atmosphere
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How do you test for metal ions?
Flame tests.
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What colour is Lithium Flame?
Red
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What colour is Sodium flame?
Yellow
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What colour is Potassium flame?
Lilac
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What colour is calcium flame?
Orange/red
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What colour is Copper flame?
Blue/green
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How can you make sure the flame test is accurate?
Clean the flame test loop in acid each time, rinse with water and check it is clean inside the Bunsen Burner flame.
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How do you test for sulfate and carbonate ions?
Add dilute hydrochloric acid and then barium chloride solution
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How do you test for halide ions?
Add dilute nitric acid and the silver nitrate solution
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How do you detect the amount of ammonia gas produced?
Damp red litmus paper turns blue, the hydrogen chloride gas reacts with ammonia to form a white smoke of ammonia chloride.
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What are instrumental methods?
Methods of analysis using machines to detect and analyse substances
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What are the advantages of instrumental methods
Sensitivity, Accurate, Carry out tests quickly
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How is a Flame Photometer test carried out?
1. Sample is vaporised in a hot flame 2. Spectrum of light emitted by ions is produced. 3. Brightness of wavelength is measured.
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What is an Alkene?
Homologous series of unsaturated hydrocarbons
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What is the general formula for alkenes, where n=number of carbon atoms
CnH2n
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What happens in the complete combustion of alkenes?
Carbon is oxidised to carbon dioxide, Hydrogen is oxidised to water vapour.
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What coloured compounds do Alkenes produce when they react with Bromine?
Colourless.
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How do you test for an Alkene?
1. Add a few drops of Bromine water. 2. Stays orange in an alkane. 3. Becomes decolourised in an alkene.
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What is an addition polymer?
Relatively large molecules made by combining smaller molecules containing C=C bonds
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What is a polymer?
A substance of high average relative molecular mass, made up of small repeating units.
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What are the properties and uses of poly(ethene)?
Flexible, cheap, good electrical insulator, used for plastic bottles and Clingfilm
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What are the properties and uses of poly(propene)?
Flexible, shatterproof, high softening point, used for buckets and bowls
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What are the properties and uses of poly(chloroethene) ?
Tough, cheap, long lasting, good electrical insulator, used for window frames, gutters and pipes, insulation for electrical wires
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What are the properties and uses of poly(tetrafluoroethene)
Tough, slippery, resistant to corrosion, good electrical conductor, used for non stick coatings for frying pans, containers for corrosive substances, insulation for electrical wires.
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What is a condensation polymer?
Where molecules join together, losing small molecules as a byproduct such as water or methanol
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What two different monomers do Polymers need?
A molecule containing two carboxylic acid groups and a molecule containing two alcohol groups
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What is an ester link?
A link that forms each time the two different monomers react together.
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What forms as an ester link forms?
One molecule of water.
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What is an example of a biological polymer?
DNA (Deoxyribonucleic acid), Proteins (amino acids)
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What is needed to make addition polymers?
Crude oil
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What is the problem of needing Crude oil to make addition polymers?
Crude oil is non renewable, supply and cost vary over time
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What is Biodegradability?
Materials that eventually rot away as microbes feed on them, breaking them down
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Why is it useful/non useful that most artifical polymers are non-biodegradable?
They last a long time, but they wont break down easily when disposed of
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How can you dispose of addition polymers?
Landfill sites, Burning, Recycling and Biodegradable polymers
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Why are landfill sites and burning bad ways to get rid of polymers?
Wont biodegrade in landfill and remain for years, burning may release toxic gases
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What do the alchols share in a homologous series?
Similar functional group, -OH, similar chemical properties, differ in molecular formula of neighbouring members by CH2 and show gradual variation in physical properties
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What do methanol, ethanol and propanol all do to react?
Dissolve in water to form a neutral solution, react with sodium to produce hydrogen, burn in air
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How do you make ethanol?
Fermentation, carbohydrates in an aqueous solution
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How is fractional distillation used to obtain a concentrated solution of ethanol?
Ethanol has a lower boiling point than water
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What do carboxylic acids have in common?
Same functional group, -COOH, Similar chemical properties, differe in the molecular formuale of neighbouring members by CH2, show gradual variation in physical properties
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How do Carboxylic acids react with carbonates?
Produce salt, water and carbon dioxide
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How do carboxylic acids react with reactive metals?
Salt and hydrogen
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How do carboxylic acids react with water?
Dissolve to produce acidic solutions
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Why are carboxylic acids weak acids?
Only partially dissociate into ions when they dissolve in water
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What is a nanoparticle?
Structures consisting only of a few hundred atoms
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What are nanoparticles useful for?
sunscreens, lightweight strong materials and future drug delivery systems
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What are the dangers of nanoparticles?
May be breathed in through skin, transported to cells, take a long time to break down and attract toxic substances to their surfaces
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Other cards in this set

Card 2

Front

What are the physical properties of the alkali metals?

Back

Good conductors of heat and electricity, Shiny when freshly cut, soft, relatively low melting points but are all solid.

Card 3

Front

What is the word equation to show how Alkali Metals react with water?

Back

Preview of the front of card 3

Card 4

Front

How does Lithium react with water?

Back

Preview of the front of card 4

Card 5

Front

How does Sodium react with water?

Back

Preview of the front of card 5
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