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Flashcards by Isabel Knight, updated more than 1 year ago
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Created by Isabel Knight
about 7 years ago
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| Question | Answer |
| Describe the process of ionic bonding. | A compound which is formed from a metal and a non-metal consists of ions. The metal atoms lose electrons to form positive ions and non-metal atoms gain electrons to form negative ions. The opposite charges of the ions mean that they're strongly attracted to each other. This is called ionic bonding. |
| What is covalent bonding? | A compound formed from non-metals consists of molecules. Each atom shares an electron with another atom. This is called covalent bonding. |
| Balance the following equation: | |
| Give the 4 stages in the limestone cycle. | |
| What is limestone used to make? | -heating powdered limestone in a kiln with powdered clay makes CEMENT -Cement can be mixed with sand and water to make MORTAR-sticks bricks together -mixing cement with sand and aggregate makes concrete |
| What environmental problems come with quarrying limestone? | -permanently changes the landscape -quarrying processes (e.g. blasting rocks with explosions) make lots of noise and dust in quiet areas. -destroys habitats -causes pollution when transporting away limestone -waste materials produce unsightly tips |
| Name 2 ways pollution is caused from using limestone to make other products. | 1)cement factories make a lot of dust which cause breathing problems 2)Energy is needed to produce cement and quicklime which will likely come from burning fossil fuels |
| Give the advantages of limestone products. | -Widely available -cheaper than granite or marble -Limestone, concrete and cement don't rot when they get wet -can't be gnawed away by insects/rodents -fire-resistant -Concrete doesn't corrode like a lot of metals do -It provides houses and roads -chemicals used in making dyes, paints and medicines come from limestone -they neutralise acidic soil/acidic lake and rivers (acid rain) -used in power station chimneys to neutralise sulphur dioxide (causes acid rain) -provide jobs for people-brings money to the local economy |
| Give the disadvantages of limestone products. | -It is more hard-wearing than marble -Has a low tensile strength and can crack -concrete is an unattractive building material |
| How can the profitability (economics) of metal extraction change over time? | -If the market price of a metal drops a lot, it might not be worth extracting it -If the price increases it might be worth extracting more -As technology improves it becomes possible to extract more metal from a sample of rock-worth extracting more than in the past |
| What is reduction and why is it affected by the reactivity series? | A metal can be extracted from its ore chemically by reduction using carbon. When an ore is reduced, oxygen is removed from it -e.g. iron(III) + carbon = iron + carbon dioxide Metals below carbon in the reactivity series can be extracted by reduction using carbon because carbon can only take the oxygen away from metals which are less reactive than the carbon itself. |
| What is Electrolysis? | The breaking down of a substance using electricity It requires a liquid to conduct the electricity called the electrolyte- which are often metal salt solutions made from the ore (e.g. copper sulphate) or molten metal oxides The electrolyte has free electrons-conduct electricity |
| How is electrolysis used to purify copper? | 1) Electrons are pulled off copper atoms at the anode (positive electrode), causing them to go into solution as Cu2+ ions 2) Cu2+ ions near the cathode (negative electrode) gain electrons and turn back into copper atoms 3) The impurities are dropped at the anode as a sludge, whilst pure copper atoms bond to the cathode. |
| How can scrap iron be used to displace copper from solution? | If some iron is put in a solution of copper sulphate, the more reactive iron will "kick out" the less reactive copper from the solution. You end up with iron sulphate solution and copper metal |
| What is a displacement? | Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound. Both metals and non-metals take part in displacement reactions. Example : Reaction of iron nails with copper sulphate solution. |
| What is bioleaching? | This uses bacteria to separate copper from copper sulphide. The bacteria get energy from the bond between copper and sulphur, separating out the copper from the ore in the process. The leachate (the solution produced by the process) contains copper, which can be extracted e.g. by filtering |
| What is phytomining? | This involves growing plants in soil that contains copper. The plants can't use or get rid of the copper so it gradually builds up in the leaves. The plant can be harvested, dried and burned in a furnace. The copper can be collected from the ash left in the furnace. |
| Give the advantages and disadvantages of metal extraction? | PROS: -makes useful products -provides local people with jobs and brings money to areas -meaning transport and health can be improved CONS: -bad for the environment- causes noise, scarring of the landscape and loss of habitats -Deep mine shafts can be dangerous for a long time after the mine has been abandoned |
| Why is recycling metals important? | -Fossil fuels provide fuel needed to mine and extract metals -fossil fuels are running out (and cause acid rain, global dimming +m climate changes) -Recycling metals only uses a small fraction of the energy needed to mine/extract (e.g. recycling copper only takes 15% energy to extract new copper) -recycling saves money -There's a finite amount of each metal-recycling conserves them -cuts down the amount of rubbish that gets sent to landfill (less pollution) |
| Give the properties of Copper and an example of what it is used for. | -good conductor of electricity (ideal for drawing out into electrical wires) -hard and strong but can be bent -doesn't react with water e.g. plumbing |
| Give the properties of Aluminium and an example of what it is used for. | -Corrosion-resistant -has a low density -pure aluminium isn't particularly strong, but forms hard, strong alloys e.g. aeroplane |
| Give the properties of Titanium and an example of what it is used for. | -low density metal -very strong -corrosion-resistant e.g. hip replacements |
| Give the basic properties of metals. | -strong (hard to break) but they can be bent/hammered into different shapes -great at conducting heat -conduct electricity well |
| How do transition metal properties make them good for everyday uses? | -Their strength and 'bendability' makes them good for making bridges and car bodies -Metals are ideal if you want to make something that heat needs to travel through e.g. saucepan -their conductivity makes them great for making electrical wires |
| Give 2 disadvantages of metals. | -Some corrode when exposed to air and water so they need to be protected (e.g. by painting) because they lose their strength and hardness. -Metal fatigue (where metals get 'tired' when strains and stresses are repeatedly put on them) leads to metals breaking which can be very dangerous (e.g. in planes) |
| Give the disadvantages of using: 1) Iron straight from the furnace 2) very pure iron | 1) Iron from the blast furnace is an alloy of about 96 percent iron, with carbon and some other impurities. It is hard, but too brittle for most uses. 2) Pure iron is soft and easily shaped because its atoms are arranged in a regular way that lets layers of atoms slide over each other. Pure iron is too soft for many uses. |
| Name 3 types of steel along with their properties and uses. | 1) LOW CARBON STEEL (0.1% carbon) -easily shaped (e.g. car bodies) 2) HIGH CARBON STEEL (1.5% carbon) -very hard, inflexible (blades for cutting tools, bridges) 3) STAINLESS STEEL (chromium added, and sometimes nickel) -Corrosion-resistant(e.g. cutlery, containers for corrosive substances) |
| How is Iron converted into steel? | Most iron from the blast furnace is converted into steel by removing some of the carbon. Carbon is removed from molten iron by blowing oxygen into it. The oxygen reacts with the carbon, producing carbon monoxide and carbon dioxide, which escape from the molten metal. Enough oxygen is used to achieve steel with the desired carbon content. |
| What are alloys? | An alloy is a mixture of two elements, one of which is a metal. Alloys often have properties that are different to the metals they contain. This makes them more useful than the pure metals alone. For example, alloys are often harder than the metal they contain. |
| Give 4 examples of alloys with their uses and properties. | 1) BRONZE = COPPER + TIN -harder than copper (e.g. medals + statues) 2) CUPRONICKEL = COPPER + NICKEL -hard + corrosion-resistant (e.g. "silver" coins) 3) GOLD ALLOYS ARE USED TO MAKE JEWELLERY -hardens the pure gold which is too soft (e.g. zinc, copper, silver, palladium + nickel) 4) ALUMINIUM ALLOYS ARE USED TO MAKE AIRCRAFT -stronger |
| What is a mixture? | A mixture consists of 2 (or more) elements or compounds that aren't chemically bonded to each other. |
| What is crude oil? | Crude oil is a mixture of many different compounds. Most of the compounds are hydrocarbon molecules (hydrocarbons are fuels e.g. petrol + diesel). There are no chemical bonds between the different parts of a mixture so the different hydrocarbon molecules in crude oil aren't chemical bonded to one another- meaning they all keep their original properties such as their condensing points. |
| Briefly describe the fractional distillation of crude oil. | The fractionating column works continuously, with heated crude oil piped in at the bottom. The vapourised oil rises up the column and the varoius fractions are constantly tapped off at the different levels where they condense. |
| What are alkanes and give their general formula? | All the fractions of crude oil are hydrocarbons called alkanes. Alkanes are made up of chains of carbon atoms (form 4 bonds) surrounded by hydrogen atoms (form 1 bond). Different alkanes have chains of different lengths. The 1st 4 alkanes are methane (natural gas), ethane, propane and butane. Alkanes = CnH2n+2 |
| Explain the trends of alkanes if the molecules are short. | 1)the more runny / LESS VISCOUS the hydrocarbon is 2)the MORE VOLATILE (turn into a gas at a lower temp.) they are 3)the MORE FLAMMABLE (easier to ignite) the hydrocarbon is. |
| Give uses of hydrocarbons. | 1)The refinery gas fraction has the shortest molecules therefore the lowest B.P. - ideal for using as bottled gas 2)The petrol fraction has longer molecules- higher B.P 3)The viscous hydrocarbons are used for lubricating engine parts + for covering roads |
| What is ethanol and give the pros and cons of using it as an alternative fuel to fossil fuels? | Ethanol can be produced from plant material- is a biofuel. It's made by fermentation of plants and is used to power cars in some places. It is often mixed with petrol to make a better fuel. PROS: is 'carbon neutral' CONS: engines need to be converted before they'll work and ethanol fuel isn't widely available |
| What is biodiesel and give the pros and cons of using it as an alternative fuel to fossil fuels? | Biofuel is a type of biofuel produced from vegetable oils (e.g. rapeseed and soybean oil). It can be mixed with ordinary diesel fuel and used to run a diesel engine. PROS: is 'carbon neutral'. engines don't need to be converted. It produces much less sulphur dioxide and 'particulates' than ordinary diesel CONS: can't make enough to completely replace diesel. expensive to make. could increase food prices |
| What is Hydrogen gas and give the pros and cons of using it as an alternative fuel to fossil fuels? | Hydrogen gas can be used to power vehicles. Hydrogen is obtained from the electrolysis of water. PROS: combines with oxygen in the air to form just water- very clean CONS: you need a special, expensive engine and hydrogen isn't widely available. it's hard to store and you need to use energy from another source. |
| What is global dimming? | Scientists found out that 25% less sunlight has been reaching the surface of the Earth compared to 50 years ago and have called this Global Dimming. They think it is caused by particles of soot and ash that are produced when fossil fuels are burnt. These particles reflect sunlight back into space. |
| Give the environmental problems crude oil can cause. | 1) OIL SPILLS (if it is transported by tanker)- birds, sea otters and whales are poisoned 2) you have to burn oil to release energy from it but that is a major cause of GLOBAL WARMING, ACID RAIN + GLOBAL DIMMING |
| What causes acid rain and what problems can it cause? | SULPHUR DIOXIDE When the sulphur dioxide mixes with clouds it forms dilute sulphuric acid which then falls as acid rain. Acid rain cause: -lakes to become acidic meaning many plants + animals will die -kills trees + damages limestone buildings + ruins stone statues -could cause human health problems. |
| Give 3 ways of reducing acid rain. | 1)Petrol and diesel are starting to be replaced by low-sulphur versions 2) Power stations now have Acid Gas Scrubbers to take the harmful gases out before they release their fumes into the atmosphere 3) Reduce usage of fossil fuels |
| What is cracking? | Cracking means splitting up long-chain hydrocarbons (are not efficient as they do not flow easily and are difficult to ignite) 1)molecules are broken down by thermal decomposition- vaporises 2) the vapour is passed over a powdered catalyst at a temp. of 400'C - 700'C 3)The long-chain molecules split apart or 'crack' on the surface of the specks of the catalyst |
| What are alkenes and give their general formula? | Alkenes are hydrocarbons which have a double-bond between 2 of the carbon atoms in their chain They are known as unsaturated becasue they can make more bonds The 1st 2 alkenes are ethene (2 carbon atoms) and propane. Alkenes = CnH2n |
| Give an example of a long molecule going through the cracking process. |
Diesel -Petrol
-Paraffin
-Ethene
for plastics
Image:
1a (image/png)
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| How can bromine water be used to test for an alkene? | An alkene will decolourise the bromine water, turning it from orange to colourless. This is because the double bond has opened up and formed bonds with the bromine. |
| When ethene is hydrated with steam, what substance is formed? Give the advantages and disadvantages of this process. | ETHANOL PROS: this is a cheap process because ethene is fairly cheap and not much of it is wasted CONS: ethene is produced from crude oil which is non-renewable meaning that using ethene to make ethanol will become very expensive |
| How is ethanol made by fermentation? Give the advantages and disadvantages of this process. | The raw material for fermentation is sugar which is converted into ethanol using yeast sugar = carbon dioxide + ethanol PROS: needs a lower temp. and simpler equipment. the raw material is renewable. can be quite a cheap fuel CONS: the ethanol isn't very concentrated |
| What are polymers? | Polymers are long chain molecules that occur naturally in living things and can also be made by chemical processes in industry. Plastics are polymers, so polymers can be extremely useful. Polymers are made when many smaller molecules join together, end to end. The smaller molecules are called monomers. |
| Give 6 uses of polymers. | 1) Light, stretchable polymers such as low density poly(ethene) are used to make PLASTIC BAGS 2) Elastic polymer fibres are used to make super-stretchy LYCRA fibre for TIGHTS 3) Waterproof coatings for fabrics 4) Dental polymers are used in resin tooth fillings 5) Polymer hydrogel wound dressings keep wounds moist 6) Memory foam (smart material)- a polymer that gets softer as it gets warmer. |
| Give 2 factors which will affect the physical properties of a polymer. | Their physical properties are affected by the temp. + pressure of polymerisation. Poly(ethene) made at 200'C and 2000 atmospheres pressure is flexible and has a low density. Poly(ethene) made at 60'C and a few atm. pressure with a catalyst is rigid and dense. |
| Why might polymers become more expensive in the future? | As crude oil resources get used up, the price of crude oil will rise so polymers will become rarer and more expensive even though they are usually cheaper than metals |
| Give 3 advantages of using vegetable oils in food. | 1) They provide a lot of energy 2) There are other nutrients in vegetable oils (e.g. oils from seeds contain vitamin E) 3) They contain essential fatty acids (needed for many metabolic processes) |
| Give 3 advantages of cooking with vegetable oils. | 1) They have higher B.P's than water-cook food quicker 2) Gives food a different flavour 3) Increases the energy we get from eating it |
| Explain the method for extracting oils from plants. | 1a) The plant material is crushed 2a) Press the crushed plant material between metal plates and squash the oil out. This is the traditional method of producing olive oil. 2b) Oil can be separated from the crushed plant by a centrifuge 1b) Or solvents can be used to get oil from plant material 3) Distillation refines oil + removes water, solvents and impurities |
| What is an emulsion? | Vegetable oils do not dissolve in water. If oil and water are shaken together, tiny droplets of one liquid spread through the other liquid, forming a mixture called an emulsion. Emulsions are thicker (more viscous) than the oil or water they contain. This makes them useful in foods such as salad dressings and ice cream. Emulsions are also used in cosmetics and paints. There are two main types of emulsion: 1) oil droplets in water (milk, ice cream, salad cream, mayonnaise) 2) water droplets in oil (margarine, butter, skin cream, moisturising lotion). |
| What are emulsifiers? | Emulsifiers are molecules with one part that's attracted to water and another part that's attracted to oil (or fat) The bit that's attracted to water is called HYDROPHILIC The bit that's attracted to oil is called HYDROPHOBIC e.g. Egg yolk contains a natural emulsifier. Mayonnaise is a stable emulsion of vegetable oil and vinegar with egg yolk. |
| What are the Pros and Cons of using emulsifiers? | PROS: -They stop emulsions from separating out-gives them a longer shelf-life -They allow food companies to produce food that's lower in fat but that still has good texture CONS: -Some people are allergic to certain emulsifiers |
| What is meant by 'primordial soup'? | The primordial soup theory states that billions of years ago, the Earth's atmosphere was rich in nitrogen, hydrogen, ammonia and methane. Lightening struck causing a chemical reaction between the gases resulting in the formation of amino acids (collected in a 'primordial soup') the amino acids gradually combined to produce organic matter which eventually evolved into simple living organisms. |
| The burning of fossil fuels is causing a rise in the level of carbon dioxide in the atmosphere. How is this affecting the oceans and the climate? | -An increase in CO2 is causing global warming- a type of climate change -The oceans are a natural store of CO2 (they absorb it from the atmosphere) - the extra CO2 we're releasing is making them too acidic which is bad for see life and means that int he future they won't be able to absorb any more CO2. |
| Name the gases that make up the Earth's atmosphere today. | 1) Nitrogen (78%) 2) Oxygen (21%) 3) Argon (0.93%) 4) Carbon Dioxide (0.038%) |
| Describe the process of the fractional distillation of air. | 1) Air is filtered to remove dust 2) It;s then cooled to around -200'C and becomes a liquid 3) During cooling water vapour condenses and is removed 4) CO2 freezes and is removed 5) The liquified air then enters the fractionating column and is heated slowly 6) The remaining gases are separated by fractional distillation. Oxygen and argon come out together so another column is used to separate them. |
| Was the 'Primordial soup' theory proven? | In the 1950's, Miller are Urey carried out an experiment to prove his theory. They sealed the gases in their apparatus, heated them and applied an electrical charge for a week. They found out that amino acids were made, but not as many as there are on Earth. This suggests the theory could be along the right lines but isn't quite right. |
| What was Alfred Wegener's theory of Continental Drift? | Alfred Wegener proposed the theory of continental drift at the beginning of the 20th century. His idea was that the Earth's continents were once joined together, but gradually moved apart over millions of years. It offered an explanation of the existence of similar fossils and rocks on continents that are far apart from each other. In 1915, he published his theory saying that about 300 years ago, there had been 1 'super-continent' called Pangaea which broke down and moved apart to create our modern day continents. |
| Why wasn't Wegener's theory accepted for many years? | 1) Other geologists thought the fact that the continent's movement being caused by tidal forces and the Earth's rotation was impossible 2) Wegener had used inaccurate data in his calculations 3) He wasn't a proper geologist- he studied astronomy By the 1960's, geologists were convinced that the Earth's crust is made of several chunks called tectonic plates which move about. |
| Describe the structure of the Earth. | 1) The CRUST- varies between 5km-50km + is surrounded by the atmosphere 2) The MANTLE- has the properties of a solid, but can flow very slowly- where radioactive decay takes place producing a lot of heat which causes the mantle to flow in convection currents 3) OUTER CORE- made from liquid nickel and iron 4) INNER CORE- made from solid nickel and iron |
| What are tectonic plates? | The Earth's crust and upper part of the mantle are broken into large pieces called tectonic plates. Occasionally, the plates move very suddenly causing an earthquake. Volcanoes and earthquakes often occur at the boundaries between 2 tectonic plates |
| Describe the Earth's early atmosphere. | Scientists believe that the Earth was formed about 4.5 billion years ago. Its early atmosphere was probably formed from the gases given out by volcanoes. It is believed that there was intense volcanic activity for the first billion years of the Earth's existence. The early atmosphere was probably mostly carbon dioxide, with little or no oxygen. There were smaller proportions of water vapour, ammonia and methane. As the Earth cooled down, most of the water vapour condensed and formed the oceans. |
| Explain how green plants evolved and produced oxygen in the evolution of the atmosphere. | The proportion of oxygen went up because of photosynthesis by plants. The proportion of carbon dioxide went down because: -it was locked up in sedimentary rocks as insoluble carbonates(such as limestone) and in fossil fuels -it was absorbed by plants for photosynthesis -it dissolved in the oceans |
| What did the build-up of oxygen in the atmosphere lead to? | The build-up of oxygen in the atmosphere killed off some early organisms that couldn't tolerate it but allowed more complex organisms to evolve. The oxygen also created the ozone layer (O3) which blocked harmful rays from the sun and enabled even more complex organisms to evolve (including humans) |
| How can vegetable oils in foods affect health? | -partially hydrogenated vegetable oil increases the amount of cholesterol in the blood so eating lots of food made with this can increase the risk of heart disease. -saturated fats are less healthy than unsaturated fats (increase the amount of cholesterol-block arteries...) |
| What is complete combustion? | When a fuel burns in plenty of air, it receives enough oxygen for complete combustion. It needs a plentiful supply of air so that the elements in the fuel react fully with oxygen. Fuels such as natural gas and petrol contain hydrocarbons. When they burn completely: -the carbon oxidises to carbon dioxide -the hydrogen oxidises to water (remember that water, H2O, is an oxide of hydrogen). In general, for complete combustion: hydrocarbon + oxygen → carbon dioxide + water |
| What is hydrogenation? | During hydrogenation, vegetable oils are hardened by reacting them with hydrogen gas at about 60ºC. A nickel catalyst is used to speed up the reaction. The double bonds are converted to single bonds by the hydrogenation. In this way unsaturated fats can be made into saturated fats. |
| What is incomplete combustion? | Incomplete combustion occurs when the supply of air or oxygen is poor. Water is still produced, but carbon monoxide and carbon are produced instead of carbon dioxide. In general for incomplete combustion: hydrocarbon + oxygen → carbon monoxide + carbon + water The carbon is released as soot. Carbon monoxide is a poisonous gas. |
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