C1 Flashcards
What are the three main fossil fuels?
Coal, (crude) oil and (natural) gas are the three main fossil fuels.
Fossil fuels are described as “finite” resources. What does “finite” mean?
“Finite” is the opposite of “infinite”. It means there is a limited supply of the fuels and that they will one day run out.
Fossil fuels are “non-renewable”. What does this mean?
“Non-renewable” means they are being used up faster than they are being formed.
What is crude oil?
Crude oil is a mixture of many different sized hydrocarbons.
What is this and what is it used for?
It is a fractional distillation column, used to separate crude oil (which cannot be used as it is) into useful products called “fractions”.
Each fraction consists of hydrocarbons of similar sizes/chain lengths.
How does fractional distillation separate the components of crude oil?
Crude oil is separated based on the different boiling points of the fractions. Lighter, shorter chains have lower boiling points. Longer, heavier chains have higher boiling points.
What happens in a fractional distillation column?
The column is hot (350-400°C) at the bottom and cooler (20-25°C) at the top.
Oil is heated at the bottom of the column and fractions boil and rise up the column.
How far they rise depends on their boiling points.
Lighter fractions with lower boiling points boil first, rise and exit at the top of the column.
Heavier fractions with higher boiling points exit nearer the bottom.
List the main fractions obtained from crude oil in the order in which they exit the column (from top to bottom).
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LPG (liquid petroleum gas), petrol, diesel, paraffin, heating oils, fuel oils, lubricating oils, bitumen (tar).
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Why do heavier fractions have higher boiling points?
In a fraction there are forces of attraction or “intermolecular forces” between the chains. These intermolecular forces must be broken if the fraction is to boil. This requires (heat) energy.
Heavier fractions are made up of larger hydrocarbons with longer chains. Longer chains have more intermolecular forces than shorter chains and so more energy is required to break them and so their boiling points are higher.
What are some of the problems associated with the extraction of transport of crude oil?
Environmental: Oil spills, damage to wildlife, coastlines and habitats, detergents used for oil spill clean up can also cause damage.
Political: UK dependent on politically unstable countries for oil, oil supply can be affected by war/conflict.
What does cracking do?
Cracking breaks up longer hydrocarbon chains (alkanes) into shorter alkane and alkene molecules.
Why is cracking so useful?
Cracking is useful because it can break up longer alkanes which are not very useful and which are in plentiful supply (e.g. bitumen, paraffin) into shorter alkanes which are more useful but in short supply (e.g. petrol).
Cracking also produces alkenes, which can be used to make plastics (very useful).
Cracking helps an oil refinery match supply of larger fractions with demand for smaller ones.
What are the conditions required for cracking?
Cracking requires a high temperature and a catalyst (aluminium oxide or porcelain chips can be used in the lab).
Why is the amount of fossil fuels being burnt increasing globally?
Fossil fuels are burnt to generate electricity in power stations and for transport (cars, trains, buses, aeroplanes, ships). Increasing global population (especially in China and India) increases demand for these and so more fossil fuels are burnt.
What factors need to be considered when choosing a fuel for a particular purpose?
Energy value, availability, storage, cost, toxicity, pollution produced and the ease of use of a fuel all need to be considered when deciding what fuel should be used for a particular purpose (e.g.heating a home, generating electricity, powering a car).
What are the products of complete combustion of a hydrocarbon?
The products of complete combustion of a hydrocarbon are carbon dioxide and water. Heat is also released during combustion.
What is the difference between complete and incomplete combustion?
Complete combustion takes place when there is a plentiful supply of oxygen and produces carbon dioxide and water.
Incomplete combustion takes place when there is insufficient (or a limited supply of) oxygen. Carbon monoxide (a poisonous gas), carbon (soot) and water are made. Less energy is released during incomplete combustion.
What are word equations for the complete and incomplete combustion of a hydrocarbon e.g.propane?
Complete: Propane + oxygen → Carbon dioxide + water.
Incomplete: Propane + oxygen → Carbon monoxide + carbon (soot) + water
What is the balanced symbol equations for the complete combustion of methane (CH4)?
CH4 + 2O2 → CO2 + 2H2O
What is the balanced symbol equations for the incomplete combustion of ethane (C2H6)?
C2H6 + 2O2 → CO + C + 3H2O
What is the composition of clean air (gases and their %)?
The percentage composition of clean air is 21% oxygen, 78% nitrogen , 1% other gases (including water vapour and 0.035% carbon dioxide). These levels stay relatively constant.
How do the processes of photosynthesis, respiration and combustion affect the levels of carbon dioxide and oxygen in the air?
Photosynthesis removes carbon dioxide from the air and adds oxygen to the air, both respiration (in living things) and combustion (burning of fuels) remove oxygen from and add carbon dioxide to the air.
What effects do deforestation and increasing population have on the composition of the air?
Deforestation (cutting down of forests) reduces the amount of carbon dioxide that can be absorbed from the air and decreases the amount of oxygen produced by photosynthesis. Levels of carbon dioxide in air therefore increase and oxygen levels decrease. Increasing population results in increased combustion of fossil fuels for energy which has the same effect (increasing levels of carbon dioxide and decreasing levels of oxygen).
Describe the main stages in the development of the Earth’s present day atmosphere.
The Earth’s atmosphere evolved over millions of years. Degassing of early volcanoes producing an atmosphere rich in water vapour, ammonia and carbon dioxide. Condensing of water vapour to form oceans. Dissolving of carbon dioxide in ocean waters. Development of photosynthetic organisms leading to an increase in oxygen levels due to photosynthesis. A relative increase of nitrogen due to its lack of reactivity and reactions of ammonia with oxygen.
What are the three main air pollutants produced by human activities?
What impacts do they have on the environment and/or health?
The three main pollutants produced by human activities are carbon monoxide (a posionous gas that can be fatal if inhaled, produced by incomplete combustion of fossil fuels e.g. petrol in cars), oxides of nitrogen (NO and NO2 produced by car engines and causing acid rain and photochemical smog), sulphur dioxide (produced by burning coal in power stations and homes and causing acid rain that can erode limestone buildings, corrode metal and damage trees and aquatic wildlife).
What is fitted to all cars to remove carbon monoxide and nitrogen monoxide from exhaust gases?
Catalytic converters are fitted to all road vehicles to remove harmful carbon monoxide and nitrogen monoxide from exhaust gases.
These gases are converted into harmless carbon dioxide and nitrogen.
What are the word and symbol equations for the reactions that take place inside a catalytic converter?
Word: Carbon monoxide + nitrogen monoxide → Carbon dioxide + nitrogen
Symbol: 2CO + 2NO → 2CO2 + N2
What is the name given to these kinds of compounds and why?
These compounds are all hydrocarbons because they contain carbon and hydrogen atoms only. They are alkanes because they contain only single C-H bonds.
List the first 6 alkanes and first 5 alkenes in correct order of their number of carbon atoms.
Alkanes - Methane, ethane, propane, butane, pentane, hexane. Alkenes - Ethene, propene, butene, pentene, hexene
What is the name of this compound?
Propene. An alkene (an unsaturated hydrocarbon with 3 carbons and a C=C double bond)
What is the difference between a saturated and an unsaturated hydrocarbon?
Saturated hydrocarbons (alkanes) contain only C-H single bonds e.g. ethane, whereas unsaturated hydrocarbons (alkenes) contain a C=C double bond e.g. ethene.
What test is used to identify if a hydrocarbon is saturated and unsaturated? What would a positive result look like for each?
Adding bromine water to a hydrocarbon will test whether it is saturated or unsaturated.
If the bromine water (orange) is decolourised by the hydrocarbon, then it is an alkene (unsaturated).
If the bromine water stays orange then the hydrocarbon is an alkane (saturated).
What is the name of the process by which alkenes are joined together into long chains?
Alkenes are joined together into long chains by the process of “addition polymerisation”.
What is the name of the monomer and the polymer in the displayed formulae shown?
Monomer - Ethene Polymer - Polyethene
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What are the conditions required for addition polymerisation?
The conditions required for addition polymerisation are high pressure and a catalyst.
Polymers (plastics) have a huge range of applications. Their uses depend on their properties. What properties would a polymer used for:
a) a lunchbox
b) a towrope
c) a storage container need?
A polymer used for a lunchbox would need to be flexible, waterproof, inert (unreactive), light and possibly transparent.
A polymer used for a tow rope would need to be strong and flexible.
A polymer used for a container would need to be strong, rigid and waterproof.
Describe how the strength of intermolecular forces between polymer molecules affects a polymer’s properties (melting point, flexibility, rigidity etc).
Polymers that have weak intermolecular forces between polymer molecules have low melting points and can be stretched easily as the polymer molecules can slide over one another.
Plastics that have strong forces between the polymer molecules (covalent bonds or crosslinking bridges) have high melting points, cannot be stretched and are rigid.
Explain why Gore-Tex is better than nylon for outdoor clothing.
Nylon is tough, lightweight and waterproof, but not breathable. Goretex has all the properties of nylon but is also breathable. This mean it allows water vapour (sweat) to escape.
How does Gore-Tex manage to be waterproof AND breathable?
The holes (pores) in the Gore-Tex membrane are too small for water droplets (rain) to pass through, but are big enough for water vapour to pass through.
Polymers are non-biodegradable. What does this mean?
Non-biodegradable means that polymers will not decay or decompose into its elements.
What are the three main ways that waste polymers can be disposed of?
Waste polymers can be disposed of in land-fill, by incineration (burning) and by recycling.
What are some of the problems associated with the use and disposal of polymers?
Some of the problems associated with the use and disposal of polymers are:
Plastics can cause litter which can threaten wildlife and habitats
Incineration can produce toxic pollutant gases
Finite reserves of crude oil are used up in the production of single-use plastics which are then just thrown away.
Why is cooking a chemical change?
Cooking is a chemical change because a new substance is formed and the process cannot be reversed (the food cannot be “uncooked”).
What happens to the proteins in eggs or meat when they are cooked?
The proteins in eggs and meat change shape when they are cooked. This is known as “denaturing”.
Why is potato easier to digest if it is cooked?
Potato is easier to digest if it is cooked because the cell walls in the potato tissue rupture (burst) which softens the potato and because starch grains in the cells swell up and spread out.
What are the main food additives found in processed foods and what do they do?
The main additives found in processed foods are:
antioxidants (prevent food reacting with oxygen)
colourings (improve the appearance of foods)
flavour enhancers (e.g. monosodium glutamate, MSG which improve the food’s flavour)
emulsifiers (help oil and water to mix and stop them separating e.g. in ice cream, mayonnaise).
What is this molecule and what does it do?
This molecule is an emulsifier molecule and it prevents oils/fats and water in foods from separating.
What do the terms “hydrophilic” and “hydrophobic” mean?
“Hydrophilic” means water-loving and “hydrophobic” means water-hating.
How does baking powder make cakes rise?
Baking powder makes cakes rise because when it is in the oven as part of the cake mix the heat of the oven breaks it down (this is known as thermal decomposition) into sodium carbonate, carbon dioxide and water.
Carbon dioxide is a gas which rises through the cake mix and is trapped as bubbles, making the cake rise.
What is the test for carbon dioxide?
The test for carbon dioxide is the limewater test. When carbon dioxide is bubbled through limewater it turns it cloudy.
What is the word equation for the thermal decomposition of baking powder (sodium hydrogencarbonate)?
Sodium hydrogencarbonate → sodium carbonate + carbon dioxide + water
What is the balanced symbol equation for the thermal decomposition of baking powder (sodium hydrogencarbonate)?
2NaHCO3 → Na2CO3 + CO2 + H2O
What is an ester and what products contain them?
An ester is a fragrance or perfume compound that can be made synthetically. Cleaning products, cosmetics, perfumes, toiletries and air fresheners contain esters to make them smell nice.
Describe how to carry out a simple experiment to make an ester.
To make an ester, mix together an acid (e.g. ethanoic acid) and an alcohol (e.g. ethanol) and heat the mixture in a hot water bath with a few drops of concentrated acid (e.g. sulphuric acid) to act as a catalyst.
State the physical properties required in a perfume and why they are needed.
A perfume needs they following properties:
Easily evaporates so that the perfume particles can easily reach the nose;
non-toxic so it does not poison you;
does not react with water because otherwise the perfume would react with perspiration;
does not irritate the skin otherwise the perfume could not be put directly on the skin;
insoluble in water so it cannot be washed off easily.
Substances that are volatile evaporate easily. Explain how a substance, such as a perfume, evaporates using particle theory.
To evaporate, particles need enough energy to overcome the attraction to other molecules in the liquid. Only weak attraction exists between particles in volatile substances such as a liquid perfume so it is easy to overcome this attraction and so the perfume evaporates easily.
Define the terms solute, solvent, solution, soluble and insoluble.
A solute is a substance that dissolves in a liquid to form a solution.
A solvent is the liquid in which a solute dissolves.
A solution is a mixture of solvent and solute that does not separate out.
Soluble describes a substance that will dissolve.
Insoluble describes a substance that will not dissolve.
If a substance is soluble it will dissolve in a given amount of solvent.
Write the equation for the making of an ester
acid + alcohol → ester + water
Ethanoic acid reacts with ethanol to make the ester ethyl ethanoate (and water).
What is the ester formed from the reaction of:
a) ethanol and propanoic acid
b) butanol and methanoic acid?
a) Ethanol + propanoic acid → Ethyl propanoate + water
b) Butanol + methanoic acid → Butyl methanoate + water
Esters can be used as solvents. They are used in nail varnish remover to dissolve nail varnish. Why does nail varnish remover dissolve nail varnish but water does not?
Water doesn’t dissolve nail varnish because the attraction between water molecules is stronger than the attraction between water molecules and particles in nail varnish. The atttraction between particles in nail varnish is also stronger than the attraction between water molecules and particles in nail varnish.
Why has the testing of cosmetics on animals been banned in the EU?
The testing of cosmetics on animals has been banned in the EU because it is expensive and considered cruel and uneccessary to test products on animals that are not directly beneficial for protecting human health.
Why do new cosmetics need to be thoroughly tested before they can be used?
Cosmetics need to be thoroughly tested to make sure they do not cause harm to people who will use them. For example, they need to be tested to make sure they do not cause irritation to the skin, trigger allergic reactions or are poisonous.
List the ingredients of paints and what they are used for.
Paint has 3 main ingredients:
- The solvent thins the paint and makes it easier to spread
- The binding medium sticks the pigment in the paint to the surface
- The pigment is the substance that gives the paint its colour.
What is the difference between oil paint and emulsion paint?
Oil paints have the pigment dispersed in an oil and often a solvent that dissolves oil. Emulsion paints are water based paints that dry when the solvent (water) evaporates.
A paint is a type of mixture called a “colloid”. What does this mean?
In a colloid the particles are mixed and dispersed with particles of a liquid but are not dissolved.
The components of a colloid will not separate because the particles are too small and light to sink to the bottom and settle, so they stay suspended in the liquid.
Milk is another example of a colloid: the tiny fat droplets are suspended in water.
How do oil and emulsion paints dry?
Paints are applied as a thin layer and dry when the solvent evaporates.
In oil paints, the solvent evaporates and the oil is oxidised by oxygen in the air.
Emulsion paints as water based paints that dry when the solvent (water) evaporates.
What are thermochromic paints and what are they used for?
Thermochromic paints are paints that contain pigments that change colour when they are heated or cooled.
Thermochromic pigments can be used for thermometers, novelty items (mugs that change colour as the drink inside them cools), and for baby’s spoons or bath toys to indicate if the food or bath water are too hot.
What are phosphorescent paints and how do they work?
Phosphorescent paints are “glow in the dark” paints that contain pigments that absorb and store energy and then release it as light energy (in the dark).
They are used on watch faces, warning signs e.g. firextinguishers and emergency light switches that might need to be located in the dark.
Radioactive substance were previously used in the these applications but were banned due to health concerns.
