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75 Cards in this Set
- Front
- Back
Name 3 examples of fossil fuels. |
Crude Oil Coal Natural Gas |
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Describe the formation of fossil fuels |
Formed naturally over millions of years. |
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Describe the supply of fossil fuels |
easy to extract finite no renewable |
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What does it mean when a resource is finite? |
Being used up much faster than it is being replaced, and there is an limited amount. |
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Describe the process of extracting and transporting crude oil |
Found in earth's crust Pump it to earth's surface Transported to refineries through pipelines or in oil tankers |
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Problems with crude oil |
Accidents can cause oil spills or slicks on the sea surface Oil can affect the wildlife including birds |
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Dealing with crude oil spills |
Detergents (but toxic and harm wildlife) |
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What type of molecule is crude oil made up of? |
Hydrocarbon (only hydrogen and carbon) |
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Why fractional distillation is possible |
Different hydrocarbons have different boiling points This means that crude oil can be separated into useful fractions that contain mixtures of hydrocarbons with similar boiling points |
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Describe the process of fractional distilation |
Heated in a fractionating column Column has a temperature gradient; it is hotter at the bottom than at the top Fractions with low boiling points exit at the top of the column and ones with high boiling points exit at the bottom |
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Name 3 properties of liquefied petroleum gas |
Contains propane and butane Gases at room temperature Can be bottom |
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Name the 2 types of hydrocarbon molecules |
Alkane Alkene |
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Describe cracking |
Large alkane molecules are broken down into alkene and alkane molecules This requires a catalyst High temperature High pressure |
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Uses of cracking |
Make more petrol from Naphtha Make alkene molecules that can be used as monomers and turned into polymers This is useful because there isn't enough petrol in crude oil to meet demand. |
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Forces and bonds in hydrocarbons |
Strong covalent bonds between the atoms Weak intermolecular forces |
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Forces in long and short hydrocarbons |
The intermolecular forces in longer hydrocarbons are stronger than in short hydrocarbons |
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What happens when you boil liquid hydrocarbons? |
The molecules move faster until all intermolecular force are broken and the liquid becomes a gas |
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What happens when fuels react with oxygen in the air? |
The fuels combust Useful heat energy is released |
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Write the word equation for complete combustion of a hydrocarbon |
Methane + oxygen --> carbon dioxide + water |
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Write the symbol equation for complete combustion of a hydrocarbon |
CH4 (g) + 2O2 (g) --> CO2 (g) + 2H2O (l) |
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What colour of flame indicates complete combustion? |
Blue |
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What happens when fuels burn without enough oxygen? |
A little less heat energy is released Carbon monoxide is produced (which is why gas appliances should be serviced regularly) |
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Write the word and symbol equation for standard incomplete combustion |
Methane + oxygen --> carbon monoxide + water 2CH4 (g) + 3O2 (g) --> 2CO (g) + 4H2O (l) |
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Write the word and symbol equation for incomplete combustion where there is very little oxygen present |
Methane + oxygen --> carbon + water CH4 (g) + O2 (g) --> C (s) + 2H2O (l) |
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What colour of flame indicates incomplete combustion? |
Yellow |
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What factors should be taken into consideration when choosing an appropriate fuel? |
Energy value (energy released per gram of fuel) Availability Ease of storage Cost Toxicity Pollution Ease of use |
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Why is complete combustion preferred over incomplete combustion? |
Less soot produced More heat energy is released No carbon monoxide is made |
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Levels of gas in the atmosphere are kept relatively constant by what? |
Respiration Combustion Photosynthesis (balances out resp. + comb.) |
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Earth's early atmosphere |
The main gases in the atmosphere used to be ammonia, carbon dioxide, and water These gases came from inside the Earth and were released through volcanoes |
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Development of Earth's atmosphere |
As plants developed, photosynthesis reduced the amount of carbon dioxide and increased the amount of oxygen As the Earth cooled to a surface temperature below 100 degrees Celsius, water vapour condensed into water and formed oceans Levels of nitrogen increased as nitrifying bacteria released unreactive nitrogen |
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Name 3 causes of increased air pollution |
Sulfur dioxide is made when fossils fuels that contain sulfur impurities are burned Poisonous carbon monoxide is formed by incomplete combustion in engines Oxides of nitrogen are formed in car engines and cause photochemical smog |
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Explain the harmful effects of sulfur dioxide |
Causes acid rain which kills plants and aquatic life, as well as eroding stonework and corroding ironwork |
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Explain how oxides of nitrogen are made in car engines |
Nitrogen and oxygen from the air react in the hot car engine, forming nitrogen monoxide and nitrogen dioxide |
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Name three key factors which have affected the levels of carbon dioxide in the atmosphere |
Burning of fossil increase CO2 Deforestation reduces photosynthesis and increase CO2 Increased world population contributes to these two factors as well |
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Explain what a catalytic converter does and how it works |
Changes carbon monoxide into carbon dioxide Contains catalysts to help pollutants react with oxygen This means less harmful gases and less pollutants are produced |
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Write the word and symbol equations for the reaction inside a catalytic converter |
Carbon monoxide + nitrogen oxide --> nitrogen + carbon dioxide 2CO + 2NO --> N2 + 2CO2 |
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How many bonds can carbon and hydrogen make? |
Carbon: 4 bonds per atom Hydrogen: 1 bond per atom |
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How are hydrocarbons made? |
Hydrogen atoms are reacted with carbon atoms to form covalent bonds This means carbon atoms share a pair of electrons with hydrogen atoms |
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Describe the structure of alkanes |
Alkanes only have single covalent bonds (they are saturated hydrocarbons) and the main chain will only contain carbon-to-carbon bonds. They have the maximum number of hydrogen atoms per carbon atom in the molecule |
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Describe the structure of alkenes |
Alkenes have at least one double carbon-to-carbon covalent bonds. They are unsaturated hydrocarbons and do not have the maximum number of hydrogen atoms per carbon atom in the molecule |
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Describe a test for the presence of (unsaturated) alkenes |
Alkenes decolourise bromine water. This reaction is a test for unsaturation; if an alkene is present, the double carbon-to-carbon bond undergoes an addition reaction with bromine water to form a colourless dibromo compound. Alkanes have no effect on bromine water. |
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Explain how polymerisation works |
Unsaturated alkenes are joined together to make a saturated polymer This reaction requires high pressure and a catalyst |
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Features of plastics that have weak intermolecular forces |
Low melting points Easy to stretch because molecules can slide over one another |
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Features of plastics that have strong intermolecular forces (covalent bonds or cross-linking bridges) |
High melting points Rigid and difficult to stretch |
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Features of nylon |
Lightweight Tough Waterproof Blocks UV light (which is harmful) |
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Uses of nylon |
Outdoor clothing Doesn't let water vapour escape and can therefore be uncomfortable |
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Features of Gore-Tex |
All the other features of nylon but also breathable, allows water vapour to escape so it's more comfortable |
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How Gore-Tex works |
The nylon fibres are laminated with a membrane of PTFE or polyurethane, making the holes in the fabric much smaller. The lamination coating is not strong enough to be used on its own, so it is used with nylon |
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Features of biodegradable plastics |
Contain special parts which dissolve easily and break up the polymer chain |
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Results of a chemical change |
New substances are formed An energy change takes place The change cannot be easily reversed |
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Effects of cooking on protein molecules |
Irreversible denaturing (changing shape and appearance) |
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Effects of cooking on potatoes and other vegetables |
Heat breaks down the cell wall and the cells become soft. Starch grains become easier to digest |
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Effects of heating on baking powder |
Sodium hydrogen carbonate decomposes to make sodium carbonate, water, and carbon dioxide. This carbon dioxide |
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Write the symbol equation for the heating of baking powder |
2NaHCO3 --> Na2CO3 + H2O + CO2 |
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Describe a test for carbon dioxide |
Limewater (a calcium hydroxide solution) is used. If carbon dioxide is present, the limewater will change from colourless to milky |
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Name 4 different types of food additive and explain their uses |
Antioxidants: stop food reacting with oxygen and going off Food colourings: improve the appearance Flavour enhancers: bring out the flavour without adding their own taste Emulsifiers: help mix oil and water |
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Describe how an emulsifier works |
The molecules in an emulsifier have two ends. One is attracted to water (hydrophilic) and the other is repelled from water (hydrophobic). This allows the oil and water droplets to be kept together. |
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Where do some cosmetics come from? (2) |
Natural resources (lavender, musk and rose) Manufactured (Synthetic) |
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What are esters? |
A family of compounds often used for perfumes. Made by reacting an alcohol with organic acid to produce ester and water. They can also be used as solvents. |
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Smells are made of ...? |
Molecules |
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Describe properties of Perfume |
Evaporate easily - can travel up the nose Not toxic - doesn't poison you Not irritant- comfortable on skin Doesn't dissolve in water (insoluble) - or it would wash off on skin. Doesn't react with water- or it would react with sweat. |
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What does it mean by 'Perfumes are volatile' ? How? |
They evaporate easily. Molecules held together by weak forces of attraction. Molecules with higher energy can overcome weak. |
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Advantages of animal testing for cosmetics |
Can prevent humans from being harmed |
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Disadvantage of animal testing for cosmetics |
Cruel to animals Animals don't have same body chemistry, so test results may not be useful. |
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Definitions of Soluble, Insoluble, Solvent, Solute and Solution |
Substances that dissolve in a liquid Substances that don't dissolve in a liquid A liquid that a substance is dissolved in Substance that get dissolved What you get when you mix a solvent and solute. |
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Properties of Solvents |
Dissolves in ethyl ethanoate (nail varnish remover) They weren't dissolve because: the attraction between water molecules is stronger than between water and varnish molecules. Attraction between molecules in nail varnish is stronger than between water and nail varnish molecules. |
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What are Colloids? |
Small, solid particles that are mixed well (dispersed but not dissolved) with liquid particles. E |
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Example of a colloid |
Paint |
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What is paint a mixture of ? |
Pigment - substance that gives paint the colour. Binding medium - oil that sticks the pigment to surface that is being painted. Solvent - thins the thick binding medium and makes it easier to coat surfaces. |
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What is the particle size of colloids ? Why? |
Very small because they stay scattered throughout the mixture. If they were too big they settle to the bottom of the mixture. |
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How does the oil-based paint (gloss) dry ? |
Solvent evaporates away. Oil-binding medium reacts with oxygen in the air (oxidation reaction) as it dries to form a hard layer. |
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What do thermochromic pigments do? |
Change colour when they are heated or cooled. |
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What can thermochromic pigments be used for? |
to coat kettles and cups to indicate temperature mood rings toys and cutlery for babies to warn if food or bath water is too hot. |
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What do Phosphorescent pigments do? |
Glow in the dark. They absorb and store energy and releases light when it is dark. |
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What were the first 'glow in the dark' paints made using? |
Radioactive material a pigments and used for things like watches. |