Chemistry C8-C12 paper 2

Theories on how life formed on earth

-3.4b years ago, simple organisms similar to bacteria appeared -these could breakdown chemicals s a source of energy -2.7b years ago, bacteria and other simple organisms e.g. algae, evolved -Algae could use energy from Sun to make own good by photosynthesis -this produced oxygen -over next billion years- O2 levels rise and algae and bacteria thrived in seas -more and more plants evolved and photosynthesised -all plants evolved -atmosphere became richer w O2 as plants colonised on land -made is posible for first animals to form -these animals couldn't make own food so relied on algae and plants for their food and on oxygen to respire -many early living microorganisms could not tolerate a high O2 level concentration, bc evolved w/o it -they largely died out as there were fewer places where they could survive

what do greenhouse gases do and what three gases are greenhouse gases? How does it work

-CO2, Methane and water vapour -w/o CO2 the earths atmosphere would be -19 degrees -earth is heated by sun -not all angry reaching the Earth warms up our planet -30% is reflected back in to space -greenhouse gases let short wave length electromagnetic radiation e.g. ultraviolet light pass through -surface of Earth cools down by emitting longer wavelength infrared (thermal) radiation -greenhouse gases absorb infrared radiation -radiation stimulates vons in molecules to vibrate, bend, and stretch more vigorously raising their temp -some of energy radiated from surface gets trapped in atmosphere as temp rises -higher proportion of greenhouse gases in air= more energy absorbed

when fossil fuels are burned, what is produced?

-Co2 -water -hydrocarbons -contain sulfur in impurities

what is the effect of a catalyst on a reaction - include what a catalyst is

-a catalyst speeds up the rate of reaction but it is not used up itself during the reaction, it remains chemically unchanged -different catalysts are needed for different reactions -catalysts are used whenever possible in industry to increase the rate of reaction and reduce energy costs (bc less fossil fuels are needed as it doesn't take as long)

What are alkenes

-a lot more reactive than alkanes -used as a starting material when making lots of other compounds and used to make polymers

what is an impure substance

-a mixture of 2 or more different elements or compounds

Crude oil facts

-a mixture of manly different compounds -most compounds in crude oil are hydrocarbons (contain only hydrogen and carbon atoms)

how is sewage sludge treated

-after spirited during primary treatment, it can be dried out and used as fertiliser on farmland to improve soil or used as a renewable energy source -digested anaerobically by microorganisms beneath surface in treatment tank -biological treatment can be carried out at a relatively high temp of 55 c or at 35c which can take 30 days to complete -high temp benefits speeding up the breakdown of organic matter but energy has to be supplied to heat the sludge -breakdown products include biogas which can be burned and used to power the sewage treatment plant or provide electricity for surrounding area -can also be further cleaned to make methane, main gas in natural gas and piped in to gas supply -or can be dried out and burnt to generate electricity

what is bioleaching and how does it work

-bacteria feed on low grade metal ores -by combination of biological and chemical processes, a solution of copper ions (leachate) can be obtained from the waste copper ore -scrap iron and electrolysis is used to extract the copper from the leachate -20% of copper comes from this method -likely to increase as sources of copper rich ores run out -slow process -can take years to extract 50% of metal from low grade ore

how to test for Carbon Dioxide gas

-bubble carbon dioxide through limewater (calcium hydroxide solution) using apparatus -record observations and explain -Result: CO2 gas turns limewater cloudy/milky safety: eye protection limewater = marble chips (Calcium carbonate) + dilute hydrochloric acid -they react to form water + CO2 -carbon makes lime water cloudy

how are sedimentary rocks formed

-build up of skeletons and shells of marine organisms at bottom of vast oceans -became covered w layers of fine sediment -eventually deposits formed sedimentary carbonate rocks e.g. limestone (containing mainly calcium carbonate) through pressure

how can you change the amount of products formed at equilibrium

-by changing the temperature at which you carry out a reversible reaction

how to solve sulfur problem

-can remove sulphur impurities before it is burnt -this happens in petrol and diesel for cars and in gas fired power stations -in coal fired power stations, suffer dioxide can be removed from the waste or flue gases by reacting it w basic calcium oxide or calcium hydroxide

how can you test the gases formed in complete combustion of a hydrocarbon

-carbon dioxide turns limewater cloudy and water turns blue cobalt paper pink (or white anhydrous copper sulphate blue )

how was CO2 removed from early atmosphere

-carbon from carbon rich atmosphere locked up within Earths crust in rocks and fossil fuels -dissolved in water of oceans -reacted e.g. w metal oxides and made insoluble carbonate compounds -these fell in to seabed as sediments and helped form more carbonate rocks

solutions to tackle global climate change- governments

-carbon taxes- taking fossil fuels and cars that burn a lot of petrol/diesel -funding research into alternative forms of energy -support biofuels (carbon neutral) - made from plant material that absorbs CO2 during photosynthesis and effectively returns it to atmosphere when burnt -incentives can be given to improve at home insulation to conserve energy -companies that produce CO2 in processing of materials can offset carbon taxes on their emissions by planting trees -other policies dictate that whenever trees are felled, new ones are planted to take place

how to test for chlorine gas

-chlorine is a toxic gas - wear hand and eye protection -add concentrated hydrochloric acid (corrosive) to a spatula of moistened potassium manganate (VII) crystals in a boiling tube held in a rack inside a fume cupboard -damp blue litmus paper turns white (as it gets bleached)

how is coal formed

-classed as sedimentary rock -formed from thick deposits of plant material such as ancient trees and ferns -when plants died in swamps, they were buried in the absence of O2 and compressed over millions of years

how to test for oxygen gas

-collect 15 cm^3 of hydrogen peroxide solution in a small conical flask -add a small amount of manganese (IV) oxide to from the end of a spatula -insert a glowing split (made by slowing out a lighted splint) in the mouth of the flask -explain observation Result: Oxygen if present will relight a glowing splint safety: wear eye protection

how to test for hydrogen gas

-collect a test tube of hydrogen gas -record observations when you hold a lightened splint at the open end of the test tube of hydrogen gas -explain observations Result: Hydrogen gas burns rapidly with a pop sound when you apply a lighted splint safety: eye protection as hydrogen is flammable

what can pure substances be

-compounds or elements but can only contain one substance -have fixed boiling and melting points eg water as it boils always at 100 degrees c

what is desalination

-converting salty water to potable, useable water -used in Middle East in some oil rich nations and on some islands with no natural sources of water apart from occasional rainwater -

problems of reducing carbon footprint

-cost implications all manufacturing and transport industries -poorer countries were not originally included in negotiations as they aren't main contributors to greenhouse emissions however restrictions could hinder their developing industries -people need info about climate change so everybody can make a positive contribution -if you use less electricity= less fossil fuel= less CO2 release -can use care less will make you healthier and reduce emissions or if you have to drive share lifts or use public transport -can also recycle waste -however to have any effect, more people must start believing that their small contributions will help

solutions to tackle global climate change- methane

-create less of a demand for beef= less cows = less methane -plant based diets offer a more efficient use of land w farmers using fields to grow crops and vegetables rather than feeding animals

other than incomplete combustion, what else can car engines produce (pollution)- global dimming

-diesel engines burn hydrocarbons w bigger molecules than those in petrol engines -when large molecules react with oxygen in an engine they don't always burn completely -tiny solid particles containing carbon and unburnt hydrocarbons are produced -these particulates get carried away by the air -they travel in to upper atmosphere reflecting sunlight back in to space causing global dimming -scientists also think that they might damage cells in lungs and even cause cancer

blurt- reversible reactions

-energy transferred from surroundings by the endothermic reaction is equal to the energy transferred to the surroundings during the exothermic reaction a good example is the thermal decomposition of hydrated copper sulphate hydrate copper sulfate <-> anhydrogenous copper sulfate + water

problems with distillation in some countries and what is flash distillation

-expensive -energy costs involved in boiling large volumes of water even through reduced pressure is used in a desalination plant -how water can be purified -flash distillation- under reduced pressure, water boils below 100 c saving some of the energy costs

why recycle iron and steel

-from cars and tin cans -recycles steel saves about 50% of energy used to extract iron and turn in to steel -helps reduce air pollution

how were crude oil and natural gas formed

-from remains of plankton deposited i muds and on the seabed -remains covered by sediments that became layers of rick the compressed over millions of years -found trapped beneath layers of rock

LCA info

-gathering raw materials -ends when all materials are returned back to environment -so LCA provides an estimate of total environmental impact resulting from all stages in the products life cycle -the outputs back into environment include atmospheric emissions, waterborne wastes, solid wastes, energy dissipation to the surroundings and any other products made in process or product being assessed

why recycle aluminium

-help conserve earths reserves of aluminium ore as on average per year, 1 person uses 8kg -aluminium is extracted from molten aluminium oxide at high temp using electrolysis -process requires huge amounts of electrical energy -recycling saves energy and money as it doesn't involve electrolysis -95% more energy saving

other than incomplete combustion, what else can car engines produce (pollution)- nitrogen and hydrocarbons

-high temp inside engine allows normal unreactive nitrogen gas in the air to react with oxygen -this reaction makes nitrogen oxides -these are toxic and can trigger peoples asthma -like sulfur dioxide, nitrogen oxides can also cause acid rain

why do lighter fractions make better fuels

-ignite more easily -burn well -have clear (less smoky) flames

what happens when you increase the pressure of reacting gases

-increases the frequency of collisions - in turn increases rate of reaction

what happens when you increase the concentration of reactants in a solution

-increases the frequency of collisions between particles which in turn increases the rate of reaction

how is LCA carried out

-listing all energy and material inputs and outputs into the environment -evaluating the potential environmental impacts from inputs and outputs -interpreting the results help make decisions about using one material, process,, product or service over another

what is the life cycle assessment (LCA) and what is it used for

-mapping the journey materials go through -used by government agencies, businesses and industry -used to assess impact on environment caused by: -getting and processing raw materials -making product and packaging -using, reusing and maintaining the products -disposing of a product at the end of its useful life

how to find out if a substance is pure or not

-melting and boiling point data can be used to distinguish pure sustances (with fixed points) from mixtures that metal or boil at a range of temperatures

examples of finite resources

-metal ores used to extract metals -crude oil used to make polymers and petrochemicals -limestone to make cement and concrete -crude oil to make the petrol, diesel and kerosene - used for transport

how are greenhouse gas levels increasing

-more fossil fuels than ever are used to make electricity, heat homes, and run cars -increases CO2 in atmosphere as the carbon from fossil fuels which has been locked up for 100 millions of years is released of CO2 in to atmosphere when used as fuel e.g. propane + oxygen = CO2 + water -methane gets in to atmosphere from swamps and rice fields and emissions from growing number of cattle from their waste -increased human population produces more waste to dispose of in landfills sites which are another source of methane gas

what are the techniques used for fresh water treatment from reservoirs and rivers

-passing the untreated water through filter beds made of sand and gravel to remove solid particles -addition of chlorine or ozone to sterilise the water by killing microorganisms or w/o adding chemical sterilising agents, by passing ultra violet light through the water

what is phytomining and how does it work

-plants that can absorb copper ions are grown on soil containing low grade copper ore -could be on heaps of discarded waste from the processing of copper rich ores -plants are then burnt and copper is extracted from copper compounds in the ash -the copper ions can be leached/dissolved from the ash by adding sulphuric acid -makes the solution (leachate) of copper sulphate -displacement by scrap iron and then electrolysis make pure copper metal

what does crude oil provide / do

-provides fuel for modern transport e.g. cars or planes -the petrol chemical industry used some hydrocarbons from crude oil as a feed stock to make new compounds for use in things like polymers, solvents, lubricants and detergents -all products from crude oil are examples of organic compounds (compounds containing carbon atoms)

the effect of temperature on a chemical reaction

-reaction happens more quickly as the temp increases -because: -particles collide more frequently and more energetically -more of the collisions occurring in a given time result in a higher proportion of particles have energy greater than the activation energy

solutions to tackle global climate change - carbon capture and storage

-reduce carbon footprint by pumping CO2 produced in fossil fuel power stations deep underground to be absorbed my porous rocks -could be done in old, redundant oil fields -would increase cost of producing electricity by 10%

environmental considerations when recycling metals

-reduces need to mine and conserves earths limited resources -prevents pollution -eg open cast mining or quarrying is often used to get copper ore from ground but huge scars are formed in landscape, creating noise and dust and destroying habitats -mines also leave heaps of waste rock -water in an area subjected by mining of metal ores can also be affected -as rain drains through exposed ores and slag heaps of waste, the groundwater can become acidic -once ores are mined they must be processed to extract metals -eg sulfide ores are heated to high temps in smelting -any sulfur dioxide gas that escaped in to the air will cause acid rain -in extraction of iron, carbon dioxide is given off which can contribute to the enhanced greenhouse effect and global warming issues -reducing these factors is why recycling metals is so important

consequences of rising levels of greenhouse gases

-rising sea levels- from melting ice caps and thermal expansion of the warmer oceans. Eg Arctic ice cap is shrinking at a rate equivalent to the Netherlands melting away each year- could cause flooding of low lying land and increased coastal erosions and some islands to disappear -increased extreme weather events- more frequent and severe storms -change in temp and amount of rainfall + its distribution - could impact food producing capacity of dif regions- dry areas will get even dryer and that monsoons in Asia will get heavier. Some places will get less suited for growing crops , some may adapt but we haven't had experience of such short timescales so nobody knows actually effect -changes in distribution of wildlife species w some becoming extinct. Rapid changes in global climate will put ecosystems around world under stress

what are alkanes

-saturated hydrocarbons -contain many hydrogen atoms as possible in their molecules -all c-c bonds -simplest type of hydrocarbon you can get -homologous series- a group of organic compounds that react in a similar way -each carbon atom forms 4 single covalent bonds

how are fossil fuels formed

-some remains of ancient living things were crushed by large scale movements on Earth and heated with in the Earths crust over a very long period of time

what are the pollutants produced by fossil fuels

-sulfur dioxide -carbon dioxide -carbon monoxide -unburnt hydrocarbons -particulates

problems with sulfur when it is burned from fossil fuels

-sulfur reacts with oxygen when a fossil fuel is burned and forms sulfur dioxide -this is acidic and toxic -bad for environment as it can cause acid rain which can damage trees as well as killing animal and plant life in lakes -acid rain can also attack buildings especially limestone buildings and metal structures

what is carbon monoxide

-toxic gas -colourless and odourless -so can't tell that you are breathing it in -red blood cells pick up carbon monoxide and carry it around blood instead of oxygen -carbon monoxide takes up the sites on haemoglobin in red blood cells that usually bond to oxygen -eventually will get starved of carbon monoxide -will get drowsy, lose consciousness and then die if not removed from source of gas

explain how the balance of CO2 produced and CO2 absorbed by CO2 sinks

-tropical rainforests and oceans are affected by human activity -as more trees are cut down for timber and to clear land= carbon dioxide increased as trees let out the CO2 they were once storing -also as temp rises, Co2 gets less and less soluble in water -this makes oceans less effective as C02 sinks

how can you extract copper from low grade copper ores

-use bacteria (bioleaching) or plants (phytomining) to help extract copper

what is potable water

-use of water for washing, cleaning and fit to drink

what is reverse and osmosis and how does it work

-used to desalinate water -uses membranes to separate the water and the salts dissolved in it -membranes can remove 98% of dissolved salts from sea water -no heating involved so it used less energy than distillation -however, energy is still needed to pressurise the water passing though and corrosion of pumps by salty water is also a problem

what are formulations

-useful mixtures made up in indefinite proportions, designed to give a products the best properties possible to carry out its function

why is it harder to recycle copper

-usually alloyed with other metals e.g. brass: copper is mixed w zinc -impure copper from recycling has to be purified using electrical wiring

what do majority of scientists think about climate change/global warming

-vast majority of peer reviewed evidence agrees that increased proportions of greenhouse gases from human activities will increase average global temp

how did nitrogen, methane and ammonia appear on earth

-volcanoes produced nitrogen gas which gradually built up in atmosphere along with small proportions of methane and ammonia gases -any methane and ammonia found in earths early atmosphere reacted with oxygen , formed by evolving algae and plants -this removed methane and ammonia from atmosphere -however nitrogen gas could build up as it is very unreactive

what is a theory to suggest how the earths atmosphere was made

-volcanoes released CO2, water vapour, H2O and nitrogen which formed the early atmosphere -water vapour condensed as earth gradually cooled down and fell as rain -water collected in hollows of crusts rock solidified and first oceans were formed -another theory states that comets colour brought water to earth. As icy comets rained down on the surface of the Earth, they melted adding to earths water supply -as Earth began to stabilise, atmosphere was prob mainly CO2 -couldve also been some water vapour and nitrogen gas and traces of methane, (CH4) and ammonia (NH3) -wouldve been little to no Oxygen -this resembles the atmosphere that are Mars and Venus -Our nearest neighbours have atmospheres made up mainly of CO2 w little to no O2 -after violent years, atmosphere remained stable, until first life appeared on Earth

how does the position of equilibrium effect a reversible reaction

-when a reaction is at equilibrium the amount of products and reactants don't have to be equal -if the equilibrium lies to the right, the concentration of products is greater than that of the reactants -if the equilibrium lies to the left, the concentration of reactants is greater than that of products

what is incomplete combustion

-when there isn't enough oxygen inside an engine -instead of all carbon in fuel turning to CO2, carbon monoxide gas is also produced

how do reversible reactions reach equilibrium

1) -as the reactants react, their concentrations fall- so forward reaction will slow down -as more products are made and their concentrations rise, the backward reaction speed up 2) after a while the forward reaction will be going at exactly the same rate as the backward one (goes at equilibrium) 3) at equilibrium, both reactions are still happening but theres no overall affect (it is a dynamic equilibrium) meaning the concentration of reactants and products have reached a balance and won't change 4)equilibrium is only reached if the reversible reaction takes place in a closed system where none of the products can escape and nothing can get in

how does crude oil work (fractional distillation)

1) crude oil is heated until most of it has turned in to gas. The gas then enters the fractionating column (and liquid bit is drained off) 2) in the column theres a temperature gradient (hot at bottom and cooler as you go up) 3) the longer hydrocarbons have high boiling points. These condense back in to liquid and drain out of the column early on, when they're near the bottom. The shorter hydrocarbons have lower boiling points. They condense and drain out much later on near the top of the column where it is cooler 4) end up with crude oil mix separated out in to different fractions. Each fraction contains a mixture of hydrocarbons that all contain a similar # of carbon so have similar boiling points

what 4 things does the rate of reaction depend on

1) temperature 2) the concentration of a solution or the pressure of gas 3) surface area 4) the presence of a catalyst

order of fuels in a fractionating column (lowest boiling point to highest boiling point)

1)LPG- liquefied petroleum gas- used for bottled gas 2)petrol - used for cars 3) kerosene -aircraft fuel 4) diesel oil- cars, buses 5)fuel oil- ships and power stations 6) bitumen (waste)- for roads and roofs

simplified stages of LCA

1. raw material extraction 2. manufacture 3. use/reuse/maintenance 4. recycle/waste management

stages of sewage treatment

1. screening- removes solid objects and grit from rest of waste water- sewage passes through metal grid that traps the large objects 2.primary treatment- in the first circular tank, solid settlements allowed to settle out from mixture, large paddles rotate, pushing solids (sludge) towards centre of tank - there the sludge is piped to a storage tank for further treatment, the watery liquid (effluent) above sludge flows in to next tank - can still contain harmful organisms 3. Secondary treatment- in second tank, useful bacteria feed on any remaining organic matter and harmful microorganisms still present, breaking them down aerobically (in presence of O2)- tank is aerated by bubbling air through waste water 4.final treatment- in last tank, useful bacteria are allowed to settle out to bottom of tank as a sediment- sediment is either recycled back in to secondary treatment tank or passed in to tank where sludge is treated- the treated water is safe enough to then be discharged back in to rivers -if necessary, can be filtered one more time or sterilised under ultraviolet light or by chlorine - however release of chlorine into rivers does case concern, as toxic organic compounds of chlorine can be formed in the environment

what are the main 2 methods used to obtain copper metal from an ore

1. use sulphuric acid to produce copper sulphate solution before extracting the copper metal 2. smelting/roasting- copper ore is heated to a high temp in a furnace with air to produce impure copper Then use impure copper as the positive electrode in electrolysis cells to make pure copper- about 80% of copper is produced by smelting. Smelting and purifying copper ores uses high amounts of energy and electricity which costs a lot of money and causes pollution in environment

when do scientists think life began

3.4 b years ago

what are the waste products of complete combustion

CO2 and H2O vapour

why is cracking useful

Fuels made from oil mixtures containing large hydrocarbon molecules are not efficient. They do not flow easily and are difficult to ignite. Crude oil often contains too many large hydrocarbon molecules and not enough small hydrocarbon molecules to meet demand - this is where cracking comes in. Cracking allows large hydrocarbon molecules to be broken down into smaller, more useful hydrocarbon molecules. Fractions containing large hydrocarbon molecules are vaporised and passed over a hot catalyst. This breaks chemical bonds in the molecules, and forms smaller hydrocarbon molecules. e.g. hexane creates butane(alkane) and ethene (alkene)

combustion of fossil fuels-how they are formed - nitrogen oxides, CO2, sulfur dioxide, particulates and Carbon monoxide

NO2- oxidation of N2 gas in air at high temp in vehicle engines CO2- complete combustion with sufficient oxygen available SO2- oxidation of sulfur impurities in fossil fuels particulates-burning diesel CO1- Incomplete combustion in limited supply of oxygen

what actually is crude oil

a fossil fuel formed by remnants of plants and animals (i.e.. plankton) that died millions of years ago -created by high pressure and temp stored remains

what is combustion

a high-temperature exothermic redox chemical reaction between a fuel and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke.

why is the homogenous series why you get such a large variety o products

because carbon atoms can form together to form different groups e.g. alkanes and alkenes

what is a chromatogram

bottom line = base line -shows what substances make up the mixture

how to test for alkenes

bromine water: -when orange bromine water is added to an alkane no reaction will happen -if it is added to an alkene, the bromine reacts with the alkene to make a colourless compound so the drone water is discoloured

how do you find out the rate of a chemical reaction

by monitoring the amount of reactants used up over time

how do scientists analyse unknown substances in solution

by using paper chromatography

what gets oxidised during combustion

carbon and hydrogen

what is produced when hydrocarbon fuels are burned in plenty of air

carbon and hydrogen in the fuel are completely oxidised so they produce carbon dioxide and water

what does incomplete combustion of a hydrocarbon produce

carbon monoxide (a toxic gas) as one of its products

different methods of cracking (compare catalytic cracking and steam cracking)

catalytic cracking: 1) cracking is the thermal decomposition reaction breaking down by heating hydrocarbons 2) first step is to heat long chain hydrocarbons to vaporise them 3) vapour passed over a hot powdered aluminium oxide catalyst 4) the long chain molecules split apart on the surface of the specks of catalyst steam cracking -can crack hydrocarbons if you vaporise them, mix with steam and then heat them at a high temperature

formula for retention factor (Rt)

distance moved by substance/distance moved by solute -can be measured and monitored against databases to identify specific substances

how to calculate the rate of reaction at a specific time on a graph

draw a tangent to the curve then calculate its gradient -the steeper the gradient = the faster the reaction

in a reversible reaction is the -> arrow endothermic or exothermic

endothermic the other direction is exothermic

increasing the temp of a reversible reaction favours to the

endothermic reaction

decreasing the temp of a reaction favours to the (exo or endo)

exothermic reaction

what do LCAs do

highlight environmental impacts and health issues when comparing products and processes but don't take in to account differences in the cost or performance -best practice includes peer review process to check the data and validity of conclusions drawn

what are the inputs and outputs of LCA

inputs- raw materials ( in raw material stage) and energy (in use/reuse stage) outputs - atmospheric emissions (in raw material stage), waterborne diseases( in manufacturing stage), solid wastes (in use/reuse stage) and coproduces in cycle stage

mean rate of a reaction formula

mass of reactions used up (g)/ time (s)

examples of alkanes

methane , ethane , propane , butane

what does a shorter carbon chain mean

more flammable the hydrocarbon is and more runny/less viscous it is, have lower boiling points

what and how much of each gas makes up the earths atmosphere

nitrogen- 78% oxygen-21% argon- 0.9% (noble gas) co2-0.04% -trace amounts of other gases (e.g. other noble gases such as neon , krypton and xenon

collision theory - refer to activation energy

particles must collide with a certain minimum amount of energy before they can react -activation energy of a reaction is the minimum amount of energy that particles must have inorder to react

mean rate of reaction formula

quantity of reactant used/time or quantity of product formed/time

what are finite resources

resources being used up at a quicker rate than they can be replaced e.g. crude oil

what does cracking mean

splitting up long chain hydrocarbons -useful as fuels (products of cracking) e.g. petrol -example of a thermal decomposition reaction

why are fossil fuels non-renewable

take so long to make that they're being used up much faster than created (not sustainable)

graph for amount of product formed and time

tallest line- faster and more reaction -relatively flat line (test tube 2)= much faster reaction than test tube 3 -test tube 3 = fast reaction

Le Chatelier's principle- what does the position of equilibrium depend on

temperature- e.g. ammonium chloride <-> ammonia + hydrogen chloride -heating this reaction moves the equilibrium to the right (more ammonia and hydrogen chloride)(and because the reaction is endothermic) and cooling moves it to the left (more ammonium chloride) pressure/volume- only effects equilibrium involving gases -decreasing volume= pressure goes up so the side at equilibrium with higher pressure will shift towards the side with fewer particles to alleviate some of the pressure , less pressure on one side would shift the equilibrium to the side with more particles to regain some of the lost pressure concentration- if equilibrium lies to the right, the concentration of products is greater that that of the reactions (because to get the reaction back to equilibrium the right side has to produce more products) -if equilibrium moves to the left, the reactants will be greater than the products

if reversible reaction is for example 100 KJ/mol what does it tell us

the reaction is endothermic

if reversible reaction is for example -100 KJ/mol what does it tell us

the reaction is exothermic

when does the rate of a chemical reaction increase

when the SA to volume ratio of any solid reactants is increased -this increases the frequency of collisions between reacting particles

example of a natural resource, use and alternative synthetic product

wool -clothes and carpets -could use acrylic fibre (polyacrlonitrile), poly(propene) instead cotton -clothes , textiles -use polyester instead