Chemistry Paper 2

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Chemistry Paper 2 by Mind Map: Chemistry Paper 2

1. C4

1.1. Group one metals = Alkali metals = Lithium (ww moves around and fizzes), Sodium,Potassium(ww fizzes + melts hot enough to ignite the gas), Rubidium, Caesium, Francium(ww violent explosion). As you go down they get more reactive.One outer electrons. They have low mp and bp, low density, soft. Form ionic compounds. Outer electron easily lost as atomic radius is larger so less energy needed to move. When they react in water they produce hydrogen gas and a hydroxide of the metal.

1.1.1. Reactivity series: (most)Potassium,Sodium, Calcium,Magnesium, Aluminium, Aluminium, Zinc, Iron,Copper, Silver(least).

1.2. Group seven metals = Halogens = Fluorine, Chlorine(rt reactive, poisonous, green gas, low bp), Bromine(rt poisonous ,red brown liquid gives off orange vapour), Iodine(rt dark grey crystalline solid, gives off purple vapour), Astatine. 7 Electrons in outer-shells.They share covalent bonds to give both a full outer shell. As you go down they become less reactive as atomic radius larger. They react with group one to form salts.

1.2.1. Group 0 = Nobel gases = Helium, Neon, Argon, Krypton, Xenon, Radon (rt all colourless gases). All made from single atoms.Full outer shell means they are inert.Bp, mp and density increase as you go down.

1.3. Displacement reaction is where a more reactive element displaces a less reactive element from a compound.

2. C5

2.1. Rate of reaction = Amount of reactant used or amount of product formed ÷ Time.

2.1.1. Rate of chemical reaction depends on: collision frequency, successful collisions, energy transfer.

2.1.2. Factors that lead to more collisions: Increasing temp(particles move faster which gives more chance of collisions), Increase concentration(More to move around so more likely to bump in), Bigger surface area(More area to work on).

2.2. Catalyst is a substance that increases ROR without being chemically changed or used up in a reaction. Enzymes are biological catalysts they speed things up in living cells: respiration, photosynthesis, protein synthesis.

2.2.1. La Chateliers Principle: Temp =If decrease temp equilibrium moves in exothermic direction, increase temp the E moves in endothermic direction,Pressure = If decrease E will go towards side with fewer moles of gas, If increase E will go to side with fewer moles of gas, Concentration= increase reactants will move to right, increase products will move left, decrease will have opposite.

2.3. At equilibrium both reactions happen but no overall effect meaning concentrations of reactants and products have reached a balance and wont change. This can only be reached if a reversible reaction takes place in a closed system.

2.3.1. Position of equilibrium can be on left or right: can lie to the right which means lots of the products and not much of the reactants, can lie to the left meaning lots of the reactants but not much of the products, also dependant on conditions.

2.3.2. Things that effect equilibrium: temp, pressure, concentration.

3. C6

3.1. A metal can be extracted by its ore chemically by reduction or by electrolysis(can also be used to purify extracted metal) or displacement reactions or biological methods.

3.1.1. Metals more reactive than carbon are extracted through electrolysis, once metal melted an electric current is passed through it and the metal is discharged at the cathode and non-metal at the anode.

3.1.2. Biological methods:Bioleaching; Use bacteria to separate metals from their ores. Phytoextraction: Growing plants in soil that contains the metals, which builds up in leafs which are then burned in furnace and can use the ash to do electrolysis.

3.1.3. Copper can be extracted by reduction with carbon where the ore is heated in a furnace - this is smelting.

3.2. Life cycles Assessment looks at each stage of a product to work out potential environmental impact of each stages: choice of material, manufacture, product use, disposal.

3.2.1. Material = Metals being mined and extracted is expensive and causes pollution, Raw materials often used for chemical manufacture comes from crude oil which requires a lot of energy and pollution. Crude oil is formed from buried remains of plants and animals. Mixture of lots of different hydrocarbons. Compounds in it are separated by fractional distillation as they have different intermolecular forces. You can get: petrol, naphtha, diesel, oil which are important for modern day. It will eventually run out as its usage has heightened as the population grows.

3.2.2. Manufacture= Use a lot of energy, pollution, waste products and their disposal, if water needed cant put back polluted water in environment.

3.2.3. Product Use = can harm environment e.g paint gives off fumes, burning fuels gives off greenhouse gases, fertilisers damage ecosystems.

3.2.4. Disposal= Often disposed at landfill which pollutes, incineration which causes air pollution. Recycling uses energy, requires a lot of sorting. Can only recycle a certain number of times Need to go for lowest energy cost option.

3.3. Cracking is splitting up long chain hydrocarbons. Form of thermal decomposition. It produces alkene molecules which make polymers. It involves heat, moderate pressure and catalyst (aluminium oxide). It helps with the supply and demand of fractions of the crude oil.

3.4. Atmosphere Phase 3- Ozone allows evolution of complex animals: oxygen killed of early organisms that couldn't tolerate but allowed development of others, oxygen created o zone layer which blocked harmful sun rays, virtually no co2 left. Todays atmosphere = 78% nitrogen, 21% oxygen, 0.04% carbon dioxide, other.

3.4.1. Atmosphere Phase 2- Green plants evolved and produced oxygen: early co2 dissolved into oceans, plants produced 02 and removed co2, eventually got locked up in fossil fuels and sedimentary rocks. Atmosphere Phase 1:Volcanoes gave out steam and co2: Earths surface was originally molten and no atmosphere. Volcanoes degassing was mainly carbon dioxide but also steam, methane, ammonia. when settled was mostly co2 and water vapour, little oxygen.

3.5. Green house effect is caused by humans, bigger population means more respiration giving out more carbon dioxide. More industrialisation, energy demand, burning fossil fuels. It keeps the earth warm as the electromagnetic radiation given by sun is absorbed.

3.5.1. Global warming (climate change) is the after math of the increased use of green houses gases.

3.5.2. Acid rain is caused by sulfur dioxide and oxides of nitrogen. It kills fish, trees and ruins statues

3.5.3. Oxides of nitrogen cause photochemical smog.

3.6. Water purification: filtration = wire mesh screens out large twings and gravel. Sedimentation = iron sulfate added to bottom which makes clump together, chlorination = gas bubbled through it to remove harmful bacteria.

3.6.1. Pollutants in tap water: Nitrates residues from excess fertilisers it prevents the blood carrying the oxygen properly, Lead compounds from lead pipes which is poisonous.