here's the summary of the entire chemistry paper 2 spec if you want me to make one of these videos for physics paper 2 remember to like share and follow so I know it's useful for you guys first up we have rates of reaction where you need to know that the rate of a reaction can be defined as the amount of reactants used up in a given time or the amount of products made in a given time a graph of the amount of reactants against time would be a downwards curve whereas the amount of products against time would be an upwards curve the steeper the gradient of the line the faster the rate of reaction so both graphs show you that the rate is the fastest at the start as the gradient is the steepest and it gradually slows down until it stops when it goes flat to find the gradient of the straight part of the line you can just do change in y against change in X but for the curved part of the line you need to draw a tangent and then find the change in y against change in X there are four factors that increase the rate of a reaction the first is temperature where as you increase the temperature of a reaction the particles get more kinetic energy and they move around at faster speeds this means there are more frequent successful collisions and more energetic collisions that are greater than the activation energy activation energy is just the minimum energy needed for two particles to successfully Collide and react the second factor is concentration or pressure where as you increase the concentration of pressure the number of particles in a given volume increases this means there are more frequent successful collisions the third factor is surface area and you can increase the surface area of a solid by breaking it up into smaller pieces the higher the surface area the more frequent collisions there will be and the faster the rate and the final factor is adding a a catalyst a catalyst is just a substance that increases the rate of a reaction without being used up it does this by providing an alternative pathway for the reaction with a lower activation energy which means more of the particles colliding will have an energy greater than the activation energy this also results in more frequent successful collisions the next topic is equilibrium where we need to First understand what a reversible reaction is this is just a reaction where the products of the reaction can react and form the original reactants you can change the direction of the reversible reaction by changing the conditions of it for example if you heat ammonium chloride it would form ammonia and hydrogen chloride this is for the forward reaction but if you were to cool the products down the reaction would take the backward route and reform the ammonium chloride the energy changes in a reversible reaction are always the same in both directions but if one side of the reversible reaction is exothermic the opposite side will always be endothermic for example if you add water to White and hydrous copper sulfate crystals it will go in the forward exothermic Direction and form blue hydr copper sulfate crystals but if you were to heat the blue copper sulfate crystals you would reform the white and hydrous copper sulfate in the reverse reaction equilibrium is achieved when you have a reversible reaction in a closed system where nothing can enter or leave when the rate of the forward reaction becomes equal to the rate of the backward reaction we say that the reaction has reached equilibrium at this point the concentrations of both the reactants and the products stay constant you can change the amounts of reactants and products in an equilibrium mixture by Shifting the equilibrium if if you shift the equilibrium to the left the amount of reactants increase and the products decrease but if you shift it to the right it's the opposite to shift an equilibrium to the left or to the right you can change one of the following factors you can use leatha's principle to predict how changing the factor will affect the equilibrium the principle states that if a change is made to the conditions of a system at equilibrium the system will respond and shift to try and counteract the change so for example if you increase the temperature of the system the equilibrium will shift to try and decrease it back to normal here are all the possible scenarios you could have so for temperature if you increase the temperature of a system at equilibrium the equilibrium will always shift to the endothermic side to try and decrease the temperature back to normal and this is the opposite if you were to decrease it for pressure If you increase pressure equilibrium will always shift to the side with fewer moles to try and counteract the change and if you decrease pressure it will shift to the side with more moles for when you change concentration of a system at equilibrium there are four scenarios you can have and this is what you would get for each of them the next topic is organic chemistry and this starts off with crude oil crude oil is a type of fossil fuel made up by ancient biomass like Plankton that was buried in mod and subjected to high pressures and temperatures for millions of years it's a non-renewable resource we get from digging up rocks and is mostly made up of hydrocarbons hydrocarbons are compounds made up of hydrogen and carbon atoms only and we use fractional distillation to separate out all the hydrocarbon components from crude oil the crude oil is first heated and most of it is turned into gas it then enters a fractionating column where there's a temperature gradient which means it's hotter at the bottom and cooler at the top the different hydrocarbons then rise up the column and condense into a liquid based on their boiling points the longer hydrocarbons with high melting points condense near the bottom while the shorter ones with low boiling points condense near the top the reason why longer hydrocarbons have higher boiling points is because they have stronger intermolecular forces between them these need more energy to overcome the longer hydrocarbons are also more viscous which means they're thicker and also less flammable than shorter ones alkanes are a type of hydrocarbon which are saturated this just means they only contain single Bonds in their structure here are the first four hydrocarbons that exist their molecular formula have a pattern that follows the general formula cnh2n+2 and by using this formula you can work out the molecular formula of any alkane when alkanes burn they undergo a combustion reaction where they react with the oxygen in the air to form carbon dioxide and water the alkanes that come out at the bottom of the fractionating column are larger and less useful to us so we break them down into smaller molecules by using a process known as cracking there are two ways you can crack a hydrocarbon catalytic cracking which involves heating the hydrocarbon and passing it over a hot powdered aluminium oxide Catalyst and also steam cracking which involves vaporizing the hydrocarbon and mixing them with steam you then heat them to very high temperatures by doing this the longchain hydrocarbons will break into short chained hydrocarbons one of which is an alkane and the other is known as known as an alken an alken is known as an unsaturated hydrocarbon which means it contains at least one carbon to carbon double bond they are more reactive than alkanes and can easily react with hogen such as bromine you can test whether you have an alkane or an alken by adding bromine water to your solution if your solution goes from Orange to colorless an alken is present and if it just stays the same as Orange it's not present alenes are useful for making polymers and as starting materials to make other chemicals topic a is all about chemical analysis and you can identify a pure substance by checking the melting point or boiling point of it a pure substance is just a single element or compound that's not mixed with any other substances they always have specific melting or boiling points so if a substance deviates from its known values then must be an impurity present in it so in this example sample 2 is the purest as it has a boiling point that's the closest to the known boiling point of water next up we have formulations which are mixtures that have been carefully designed as a useful product they are complex mixtures where each chemical has a particular purpose for example for paint it has pigment in it which provides the color binder which holds the pigments in place and a solvent which dissolves the components into the paint other examples of formulations are tablets for medicine fuels Alloys fertilizers and Foods next up we have chromatography which is used to separate and identify components in a mixture it contains a mobile phase where the molecules can move and a stationary phase where the molecules can't move in normal paper chromatography the water or solvent is the mobile phase whereas the paper itself is the stationary phase if a component in a mixture spends longer in the mobile phase it will move up with it more so a component that's more soluble in the solvent always moves further up the chromatography paper on the other hand if a component is more attracted to the stationary phase it will spend longer in it so it will not travel up as far the end result of chromatography is known as a chromatogr and the number of spots on it tells you the number of components in the mixture this means if you only have one spot the whole sample is pure you can identify what the components are by finding the RF values of it this can be found by dividing the distance moved by the substance by the distance moved by the solvent you can then compare the RF values to known data to identify what the component is you can identify different gases by using four different tests to test for hydrogen you can add a lighted splint to the gas and if there's a squeaky pop then hydrogen is present for oxygen you add a glowing splint and it should relight for carbon di oxide you bubble the gas through lime water and it should turn cloudy and for chlorine you add blue litmus paper and it should bleach white topic 9 is all about the atmosphere for the first few billion years after the earth was formed it was molten and its atmosphere was formed from gases given off by volcanoes they were mostly water vapor carbon dioxide methane ammonia and nitrogen as the planet cooled the water vapor condensed to form oceans and the oceans absorbed carbon dioxide they also helped to formation of carbonate rocks which created sediments which reduced the carbon dioxide in the air the nitrogen released by volcanoes were very unreactive so their levels built up over time around this time there was virtually no oxygen present but when algae first developed they photosynthesized and converted carbon dioxide in the air into oxygen this raised the oxygen levels in the atmosphere which allowed plants to evolve and this released even more oxygen and removed even more carbon dioxide from the air eventually the oxygen levels were so high that animals were allowed to evolve and and when some of these organisms died some of their remains formed sedimentary rock and others were buried in mud and formed fossil fuels both of these processes caused more carbon dioxide to be removed from the atmosphere and this led to our current atmosphere this contains 78% nitrogen 21% oxygen and 1% of all the other gases these are mostly noble gases only around 0.04% of the atmosphere is made up of carbon dioxide carbon dioxide along with methane and water vapor are known as greenhouse gases and greenhouse gases are all important for keeping the earth warm short wavelength heat radiation from the Sun reaches the Earth's surface and is reemitted as long wavelength radiation some of the long wavelength radiation is then reiated by some of the greenhouse gases back towards the Earth which causes it to warm up human activities have increased the amount of greenhouse gases in the atmosphere and this has increased the greenhouse effect examples include fossil fuel combustion which has released carbon dioxide into the atmosphere farming where animals such as cow release methane into the atmosphere due to their digestive processes and deforestation where cutting down trees has meant there are few available for photosynthesis and taking in carbon dioxide from the atmosphere this increase in greenhouse gases can lead to global warming where the average global temperature of the earth increases and this can lead to the melting of polar ice caps rising sea levels and flooding extreme weather and loss of animal habitats carbon footprint measures the amount of greenhouse gases given off by an individual product service or event reducing the carbon footprint is important for tackling global warming and this can be done by taking Public's transport instead of private cars reducing the consumption of meat Recycling and reusing materials and using renewable energy resources but greenhouse gases are not the only substances that affect our atmosphere other forms of pollution include carbon monoxide that's released due to the incomplete combustion of hydrocarbons this is when there's not enough oxygen available carbon monoxide is a toxic odorless and colorless gas which is hard to detect and prevents hemoglobin in the blood from carrying oxygen it can lead to fainting Comas and even death carbon particulates also known as sit can also be forms during incomplete combustion and this can cause respiratory problems and global dimming this is where less Light reaches the Earth's surface sulfur dioxide is another pollutive gas produced by burning coal containing sulfur impurities and nitrogen oxides are formed in car engines where nitrogen and oxygen both react both of these can cause respiratory problems and they can also cause acid rain when mixed with the water inside clouds the final Topic in chemistry is on using resources and the first part is on the Earth's resources for human uses these can be things like warmth shelter food and transport some of these can be renewable and some can be non-renewable it's important that humans conserve the non-renewable resources by recycling materials reusing products and reducing the use of them in the first place this could be for materials like glass metals and even plastic and by doing this you cons serve the resource and minim waste so Metals come from metal ores which are an example of a non-renewable finite Source they have been increasingly harder to find and extract and have caused a lot of damage to the environment there are two methods you need to know about that we use to extract metals from low grade ores these are ores with only a small amount of metal in them the first is phytomining which involves growing plants on soils containing metal compounds these plants absorb the compounds and then they are harvested and burnt the burnt ash contains a lot of the metal compounds fire leaching is the second method and involves introducing bacteria to an ore where they produce a leate solution this contains a lot of the metal compounds both of the products from phytomining and bioleaching can be used to extract pure metal you first dissolve them in acid and use either displacement with a more reactive metal or electrolysis to form a pure metal water treatment is another important process that humans carry out it involves forming potable water which is just water that's safe to drink you start off by choosing a suitable water source such as surface water or ground water and passing it through filter beds these include wire meshes to remove large particles and sand beds to remove smaller particles you then sterilize the Water by adding chlorine ozone or UV light to it if a country has less fresh water sources available they can use desalination methods to remove salt from salty water this makes it pable you can either use distillation for this which involves boiling and condensing the water or reverse osmosis which involves using a membrane to allow only water particles to pass through it and no salt ions both of these methods require a lot of energy and are very expensive waste water which comes from sewage also needs to be treated before being returned to the environment it involves screening and grit removal where large objects are removed then sedimentation where heavy solids settle to the bottom once this is done the water at the top known as the effluent undergoes aerobic biological treatment this is where bacteria are used to consume the organic matter in the water then it's ready to be released back into the environment the waste that comes from the sedimentation step is known as the sludge and it undergoes anerobic digestion this is where bacteria break down the sludge with no oxygen to form methane that can be used for fertilizers and natural gas the last part is on life cycle assessments which is a method that can be used to evaluate the environmental impact of a product through all stages of its life this includes four stages the initial stage where raw materials are collected from the environment manufacturing which is the process of turning raw materials into finished products and prepping them for sale sale use which is how the product is used by the consumers and how efficiently it operates and Disposal which is what happens to the product after it can no longer be used here's an example of a life cycle assessment on shopping bags