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Chemistry AQA Unit 1 GCSE
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- 1What are the symbols for: a) calcium, b) carbon, c) sodium?a) Ca, b) C, c) Na.
- 2Which element's properties are more similar to magnesium's: calcium or iron?Calcium
- 3Describe how you would work out the electronic structure of an atom given its atomic number.Use the Electron Shell Rules. Fill the first shell up with 2 electrons, then the second up with 8, and the third one up with 8, until you have used up all the electrons.
- 4Describe the process of ionic bonding.When a non-metal and a metal bond, the metal atoms lose electrons to form positive ions and the non-metal atoms gain electrons to form negative ions. The opposite charges of the ions means that they're strongly attracted to each other.
- 5What is covalent bonding?Covalent bonding is bonding between two non-metal atoms which involves the use of molecules.
- 6Write down the symbol equation showing the thermal decomposition of limestone.CaCO3 -> CaO + CO2
- 7What products are produced when limestone reacts with an acid?A calcium salt, carbon dioxide and water.
- 8What is calcium hydroxide used for?It can be used to neutralise acidic soil in fields, and in the limewater test for carbon dioxide.
- 9Name three building materials made from limestone.Cement, mortar and concrete.
- 10What's the definition of an ore?A rock that contains enough metal to make it worthwhile extracting metal from it.
- 11Explain why zinc can be extracted by reduction with carbon but magnesium can't.Zinc is less reactive than carbon, and is lower than it in the reactivity series, but magnesium is more reactive than carbon.
- 12Give a reason why aluminium is an expensive metal.Aluminium is extracted using electrolysis, which is an expensive process.
- 13What is electrolysis?Electrolysis is the breaking down of a substance using electricity.
- 14Describe the process of purifying copper using electrolysis.The electrons are pulled off the copper atoms at the positive anode, which causes them to go into the solution as Cu2+ ions. The Cu2+ ions near the cathode gain electrons and turn back into copper atoms. The impurities are dropped at the anode as a sludge, whilst pure copper atoms bond to the cathode.
- 15Describe how scrap iron is used to displace copper from solution.When scrap iron is added to the solution. the more reactive iron will displace the copper, and so you will end up with iron in the solution and the copper.
- 16What is the name of the method where plants are used to extract metals from soil?Phytomining
- 17Give three reasons why it's good to recycle metal.It only uses a small fraction of the energy needed to mine and extract a new metal, recycling saves money, and it conserves finite metal resources.
- 18Give three properties of metals.They are strong (but can be bent and hammered into different shapes), they're great at conducting heat and can conduct electricity.
- 19Briefly describe two problems with metals.Some of them corrode when exposed to air and water and so have to be protected. They can become "tired" and break due to metal fatigue.
- 20What is the problem with using a) iron straight from the blast furnace b) very pure iron?a) It is only 96% iron and 4% impurities like carbon. b) It is far too bendy for most uses.
- 21Give two examples of alloys and say what's in them.Low carbon steel (0.1% carbon) which has iron and carbon, and bronze, which contains copper and tin.
- 22What does crude oil consist of? What does fractional distillation do?Crude oil is a mixture of many different compounds, mostly hydrocarbons. Fractional distillation breaks crude oil into its fractions.
- 23What's the general formula for an alkane?Cn H2n+2
- 24Is a short-chain hydrocarbon more viscous than a long-chain hydrocarbon? Is it more volatile?A short-chain hydrocarbon is less viscous, and more volatile.
- 25Name three pollutants released into the atmosphere when fuels are burned. What environmental problems are associated with each?Carbon dioxide: global warming/the enhanced greenhouse effect
Sulfur dioxide/oxides of nitrogen: acid rain
Particulates: global dimming - 26List three ways of reducing acid rain.Removing it from fuels before they are burnt, taking out harmful gases before they release their fumes into the atmosphere, cutting down the use of fossil fuels.
- 27Has the theory of global dimming being proven?No, some scientists think it was caused by faulty recording equipment.
- 28List three alternative ways of powering cars. What are the pros and cons of each?Ethanol. It is carbon neutral, and the only other product is water. Engines need to be converted, it isn't widely available, and increase in food prices.
Biodiesel. It's carbon neutral, doesn't require engines to be converted, produces less sulfur dioxide and particulates. Increase in food prices.
Hydrogen Gas: Very clean. Needs a special, expensive engine, isn't widely available, needs energy from another source to make it, hard to store. - 29What is "cracking" Why is it done?Cracking is the splitting up of Long-chain hydrocarbons by passing vapour over a hot catalyst. It is done to make long-chain hydrocarbons smaller so that they are more useful.
- 30Give a typical example of a substance that is cracked, and the products that you get from cracking it.Kerosene, which makes octane and ethene.
- 31What kind of carbon-carbon bond do alkenes have?A double bond.
- 32What is the general formula for alkenes?CnH2n
- 33When ethene is hydrated with steam, what substance is formed?Ethanol
- 34What are polymers? What kinds of substances can form polymers?Polymers are lots of monomers joined together to form very large molecules. They are made from alkenes.
- 35Give two factors which affect the physical properties of a polymer.Temperature and pressure.
- 36List four uses of polymers.Plastic bags, memory foam, waterproof coatings for fabrics, and resin tooth fillings.
- 37Why might polymers be more expensive in the future?Crude oil is running out, and it may be prioritised to make other substances.
- 38Why do some oils need to be distilled after they have been extracted?To remove water, solvents and impurities.
- 39List two advantages of cooking with oil.Food can be made quicker as oil has a higher boiling point than water, and it carries the flavour and intesifies it.
- 40Apart from cooking, list a use of vegetable oils.Biofuels.
- 41What kind of carbon-carbon bond do unsaturated oils contain?Double carbon carbon bond.
- 42What happens when you react unsaturated oils with hydrogen?They become hydrogenated and more solid as they are hardened because it opens up the double bond.
- 43Why do some foods contain partially hydrogenated vegetable oil instead of butter?It gives them a longer shelf-life, and is cheaper.
- 44What is an emulsion? Give an example.An emulsion is a mixture of oil and water. An example is milk.
- 45How do emulsifiers keep emulsions stable?Emulsifiers are molecules with one part (the tail) that's attracted to oil or fat (hydrophobic) and another part (the head) that's attracted to water (hydrophilic). The head latches on to water molecules. The tail latches on to oil or fat. When you shake the oil and water with the emulsifier, the oil droplets form with a coating of emulsifier, so it won't separate out.
- 46Suggest one problem of adding emulsifiers to food.People may be allergic to the emulsifiers.
- 47Give one reason why Alfred Wegener's theory of continental drift wasn't accepted for a long time.His calculations were incredibly inaccurate and so many people did not believe him.
- 48What can be found beneath the Earth's crust?The mantle.
- 49Why can't scientists accurately predict volcanoes and earthquakes?Tectonic plates have unpredictable movements and so there are almost no clues.
- 50Name the two main gases that make up the Earth's atmosphere today.Oxygen and nitrogen.
- 51Explain why today's atmosphere is different from the Earth's atmosphere.Plants evolved, and absorbed all the early carbon dioxide through photosynthesis, and in return put oxygen into the atmosphere. The ocean also stored some.
- 52What is meant by primordial soup?The primordial soup is the collection of amino acids that formed from hydrocarbons, ammonia and other gases when lightning struck and caused them to react.
- 53Why do we fractionally distil air?To get a variety of products that we can use in industry.
- 54The 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?This is making oceans more acidic and may make them unable to store more carbon dioxide in the future. It is also causing global warming.
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- Descripción
- Some questions and answers for the AQA Chemistry specification for Unit 1.
- Creado por
- Mike Schmidt
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