C6 Global Challenges Flashcards
What are natural materials?
Chemicals, or mixtures of chemicals that come from living things (cotton & paper- plants, silk & wool- animals).
What are synthetic materials?
Chemicals, or mixtures of chemicals, which have been produced by chemical synthesis.
Describe in terms of intermolecular forces and bonds how crude oil needs different boiling points to break it up.
When crude oil is heated the molecules are supplied with extra energy; thus the molecules moves about more. Eventually, a molecule may have enough energy to overcome the intermolecular term-54forces that keep it with the other molecules. The covalent bonds are much stronger meaning you don’t end up with small molecules. The intermolecular forces are easier to break in smaller molecules in comparison to larger ones. Meaning more energy is needed to break larger hydrocarbons out of crude oil.
What is crude oil made of?
Hydrocarbons- compounds made entirely of hydrogen and carbon atoms. Their properties change as the chain get longer. There are strong covalent bonds between the carbons and hydrogens within each hydrocarbon molecule. There are intermolecular forces of attraction between different hydrocarbon molecules. Only a small percent of it is used for chemical synthesis the rest if used for fuel.
What are the uses of crude oil?
It is used for fuels, to make plastics such as polyethylene, small amounts of hydrocarbons are used to make new compounds for use in thinks such as plastics, medicines, fertilisers and even food.
How is crude oil separated?
Into fractions by fractional distillation depending on the chain length. Smaller molecules have a lower boiling point, very volatile, flow easily and are easy to ignite. Vis Versa
What happens in fractional distillation?
The crude oil is heated at 400°C for the hydrocarbons to be evaporated, this passes into a fractional distillation column at the bottom. The vapour moves up the FD column and cools. Its hotter and the bottom and cooler at the top. Each fraction condenses when it has cooled below its boiling point (the larger hydrocarbon molecules with a high boiling point condense lower down the column, and the smaller molecules with a low boiling point condense higher up). Other gases will leave at the top of the tower. The fractions can then be used as fuels, lubricants and the raw materials for chemical synthesis
What are the properties and uses of polythene?
It has a low density, so is light, and is flexible and easily moulded. It can be used for plastic bags and containers.
What are the properties and uses of polystyrene?
It has a low density, so is light, and it is stiff and water resistant. It is also a thermal insulator. It can be used for coffee cups, meat trays, egg cartons and in the protection of appliances.
What are the properties and uses of nylon?
It has a low density, so is light, and it is tough and waterproof. It also blocks UV light. It can be used for clothing and climbing ropes.
What are the properties and uses of polyester?
It has a low density, so is light, and is tough and waterproof. It can be used for clothing and bottles.
What is polymerisation?
The chemical process during which hydrocarbon monomers are joined to make longer strings of molecules (polymers).
How can polymerisation be used?
Polymers have different physical properties depending on how their molecules are arranged and held together, meaning they have different uses. For example, Carrier bags (strong and waterproof), window frames (unreactive and doesn’t rot), non-stick frying pans. Heat-resistant polymers such as melamine resin and polypropene are used to make plastic kettles.
Why have polymers replaced natural materials for some uses?
They have more benefits in comparison to the traditional materials. For example, synthetic fibers like nylon are used to replace fabrics as they are lighter, more durable, water- resistant and cheaper. The main down-side is that they aren’t breathable making them uncomfortable.
What happens if polymer chains are packed close together or spread out?
If the polymer chains are packed close together, it will have a high density.
If a polymer chains are spread out the material will have a low density
What happens if the polymer chains are held together by weak forces?
If polymer chains are held together by weak forces then they are free to slide over each other. The bonds holding the atoms together are strong but the forces between molecules are weak. This means that the material (plastic) can be stretched easily (is flexible),will have a low melting point won’t be stiff, won’t be hard.
What happens if the polymer chains are held together by strong forces?
If a polymer chain is held together by strong forces then they have high melting points and can’t easily be stretched as the crosslinks hold the chains firmly together. Crosslinks are chemical bonds between the polymer chains and hold them in a regular structure. It means it will be very strong, stiff hard and have a high melting point.
Why is rigid PVC used in windows?
It is weather-resistant, strong, and durable; making window frames more secure. And do not need constant painting.
What is natural rubber?
A mass of long-chain molecules, where the molecules are held together by very weak intermolecular forces. This makes it flexible and gives it a low melting point (less energy is needed to separate the molecules).
What is vulcanised rubber?
A mass of tangled molecules, held together by cross-links, giving it strong covalent bonds between the molecules. This makes it more rigid, and gives it a high melting point (more energy is needed to separate the molecules). It is used for conveyor belts and car tyres.
How does chain length affect affect a polymer?
Depending on the length shorter chains will have weaker forces of attraction between molecules (compared to long chains) so the polymer chains can easily slide past each other, making the material flexible.
It will also have weak forces of attraction, it requires less energy to separate the molecules out of the solid structure and into a liquid formation, therefore it will have a low(er) melting point than a long chained polymer
Vis Versa.
What is the effect of increasing or decreasing the chain length?
Making a polymer chain longer will mean it will be less flexible, a higher melting point, stiffer and stronger.
Making a polymer chain shorter will mean it will be flexible, low melting point, less stiff and weaker.
What is the effect of cross-links?
These agents chemically bond the polymer chains linking them together.
These cross-links between the molecules mean that the molecules are locked in a regular arrangement which stops the chains from uncoiling and slipping over each other. The result of this is that is makes the rubber less flexible, stronger , stiffer and harder.
It also gives the rubber a high melting point because more energy is needed for the molecules to separate and break out of the solid thus more heat resistant.
What is vulcanisation?
A type of cross-linking, where sulphur atoms join rubber molecules. This creates vulcanised rubber.
What is the effect of adding plasticisers?
Plasticisers are usually an oily liquid with small molecules which can be added to polymers during their manufacture.
The small molecules sit between the polymer chains, they push the polymer chains further apart, which weakens the forces between them.
This means that less energy is needed to separate them and they slide over each other more easily.
What is the effect of making a polymer crystalline?
In a crystalline polymer, the molecules are lined up in a regular way (in neat lines) as in a crystal. It has straight chains with no branches so that the chains can fit close together. This means that the forces between the molecules are slightly stronger and more energy is needed to separate them so it has a higher melting point. As more chains are packed in, it has a higher density, and is stronger. The branches stop the molecules from packing neatly.
Batch
Certain Times. Flexible, Low Start-up Cost. But is Labour Intensive and changing quality e.g Drugs.
Continuous
All the time. Specific, Automatic (less labour), Consistent quality, Huge start up costs. e.g. Haber Process.
How are hazardous chemicals identified?
With hazard symbols- Corrosive, Explosive, Flammable, Oxidising, Harmful, Toxic.
How can safety around hazardous chemicals be ensured?
Following certain safety precautions- wearing gloves and goggles, washing hands before and after use, safety screens, using small amounts at low concentrations, ventilation or using a fume cupboard, no food and drink, keeping flammable substances away from naked flames.
The lithosphere
Made up of the crust and upper mantle.
The hydrosphere
Made up of the oceans and rivers.
Atmosphere
Layer of gases surrounding Earth.
Atmosphere contains
Mainly Nitrogen and Oxygen
Metal ore
A rock that contains minerals
Haematite formula
Fe3O4
Aluminium ore
Bauxite - Al2O3
Copper ore
Copper pyrite - CuFeS2
Gold ore
Gold - Au
Iron ore
Haematite - Fe2O3
Sodium ore
Rock salt - NaCl
Elements in order of reactivity reduced by electrolysis of molten ores.
Potassium, Sodium, Calcium, Magnesium, Aluminium.
Elements in order of reactivity reduced using carbon.
Zinc, Iron, Tin, Lead, Copper.
Elements in order of reactivity which occur uncombined.
Silver, Gold
Way of remembering reactivity series
Please Stop Calling Me A Careless Zebra Instead Try Learning How Copper Saves Gold Prick
Potassium Sodium Calcium Magnesium Aluminium Carbon Zinc Iodine Tin Lead Hydrogen Copper Silver Gold Platinum
Extracting Aluminium - Sodium hydroxide is used
To remove impurities from the Bauxite
Extracting Aluminium - Main impurities
Silica and iron oxide.
Extracting Aluminium - Carbon to make the electrodes and electrical energy goes into making the electrolysis cell.
Carbon dioxide and oxygen come out leaving pure aluminium.
Metal life cycle - Mining
Produces large amounts of waste rock. Mordern mines have ventilation shafts and sensors to test air qualitity.
Metal life cycle - Processing ores
Most ores can have as little as 0.4% or actual metal and still be profitable, which means 99.6% is waste rock.
Metal life cycle - Metal extraction
Needs large volumes of water and energy and give off air pollutants.
Metal life cycle - Metals in use
Lighter transport can reduce fuel consumption and emissions.
Metal life cycle - Recycling
Greatly reduces waste and pollution.
What are three useful products of the chemical industry?
Food additives (preservatives, colourings, flavourings)
Cleaning and decorating products (bleach, dye)
Fertilisers (ammonia)
Give an example of a chemical that is produced on a massive scale in the chemical industry
Sulfuric acid
Give two uses of sulfuric acid
Car batteries
Fertiliser production
Give an example of chemicals that are produced on a smaller scale within the chemical industry
Pharmaceuticals
How many people are employed in the chemical industry within the UK alone?
200,000
What industry has the highest portion/largest sector within the chemical industry?
Pharmaceuticals - 37%
Where are the chemicals sold?
Some sold directly to consumers, and others sold to other industries as raw materials for other products
Effect of the chemical industry on the economy in the UK?
Makes up a huge chunk of our economy
What are the 7 stages involved in chemical synthesis?
- Choosing the reaction
- Risk assessment
- Calculating quantities of reactants
- Choosing apparatus and conditions
- Isolating the product
- Purification
- Measuring yield and purity
Chemical synthesis: Give some examples of stage 1, choosing the type of reaction
Neutralisation
Thermal decomposition
Precipitation
Chemical synthesis: Give some examples of stage 2, the risk assessment
Identifying hazards
Assessing who might be harmed
Deciding the action that can be taken to reduce the risk
Chemical synthesis: Give some explanation of stage 3, calculating the quantities of reactants
Using the equation, chemists can calculate how much of each reactant is needed to produce a certain amount of product. This is important because you need to know how much of each raw material is required to ensure there is no waste - since waste costs money
Chemical synthesis: Give some explanation of stage 4, choosing the apparatus and conditions
Apparatus must be the correct size (for amount of product and reactants), as well as strength (type of reaction, e.g explosive or gives off heat)
Must decide the temperature to carry out the reaction at, what concentrations should be used and whether or not to use a catalyst
Chemical synthesis: Give some explanation of stage 5, isolating the product
Upon finishing the reaction, products may need to be separated from the reaction mixture. This could involve…
Evaporation (if product has been dissolved)
Filtration (if product is an insoluble solid)
Drying (to remove any water)
Chemical synthesis: Give some explanation of stage 6, purification
Isolating the product and purification go together. Isolating the product helps to purify it. Crystallisation can be useful in the purification process
Chemical synthesis: Give some explanation of stage 7, measuring yield and purity
Yield tells you the overall success of the process, purity must also be measured
Why is it important for pharmaceuticals to be very pure, of which is increased through isolation?
Because these are drugs intended for human consumption, impurities could do more harm than good
Why is it important for petrochemicals to be very pure, of which is increased through isolation?
If there are impurities present or contaminants in petrol products, they could damage the car’s engine
