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75 Cards in this Set

  • Front
  • Back

Name 3 examples of fossil fuels.

Crude Oil


Coal


Natural Gas

Describe the formation of fossil fuels

Formed naturally over millions of years.

Describe the supply of fossil fuels

easy to extract


finite


no renewable

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.

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

Problems with crude oil

Accidents can cause oil spills


or slicks on the sea surface


Oil can affect the wildlife including birds

Dealing with crude oil spills

Detergents (but toxic and harm wildlife)



What type of molecule is crude oil made up of?

Hydrocarbon (only hydrogen and carbon)



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

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

Name 3 properties of liquefied petroleum gas

Contains propane and butane


Gases at room temperature


Can be bottom

Name the 2 types of hydrocarbon molecules

Alkane


Alkene

Describe cracking

Large alkane molecules are broken down into alkene and alkane molecules


This requires a catalyst


High temperature


High pressure

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.

Forces and bonds in hydrocarbons

Strong covalent bonds between the atoms


Weak intermolecular forces

Forces in long and short hydrocarbons

The intermolecular forces in longer hydrocarbons are stronger than in short hydrocarbons

What happens when you boil liquid hydrocarbons?

The molecules move faster until all intermolecular force are broken and the liquid becomes a gas



What happens when fuels react with oxygen in the air?

The fuels combust


Useful heat energy is released



Write the word equation for complete combustion of a hydrocarbon

Methane + oxygen --> carbon dioxide + water

Write the symbol equation for complete combustion of a hydrocarbon

CH4 (g) + 2O2 (g) --> CO2 (g) + 2H2O (l)

What colour of flame indicates complete combustion?

Blue

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)



Write the word and symbol equation for standard incomplete combustion

Methane + oxygen --> carbon monoxide + water


2CH4 (g) + 3O2 (g) --> 2CO (g) + 4H2O (l)

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)

What colour of flame indicates incomplete combustion?

Yellow

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



Why is complete combustion preferred over incomplete combustion?

Less soot produced


More heat energy is released


No carbon monoxide is made

Levels of gas in the atmosphere are kept relatively constant by what?

Respiration


Combustion


Photosynthesis (balances out resp. + comb.)

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



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

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



Explain the harmful effects of sulfur dioxide

Causes acid rain which kills plants and aquatic life, as well as eroding stonework and corroding ironwork

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

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

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

Write the word and symbol equations for the reaction inside a catalytic converter

Carbon monoxide + nitrogen oxide --> nitrogen + carbon dioxide




2CO + 2NO --> N2 + 2CO2

How many bonds can carbon and hydrogen make?

Carbon: 4 bonds per atom


Hydrogen: 1 bond per atom

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

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

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

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.

Explain how polymerisation works

Unsaturated alkenes are joined together to make a saturated polymer


This reaction requires high pressure and a catalyst

Features of plastics that have weak intermolecular forces

Low melting points


Easy to stretch because molecules can slide over one another

Features of plastics that have strong intermolecular forces (covalent bonds or cross-linking bridges)

High melting points


Rigid and difficult to stretch

Features of nylon

Lightweight


Tough


Waterproof


Blocks UV light (which is harmful)

Uses of nylon

Outdoor clothing


Doesn't let water vapour escape and can therefore be uncomfortable

Features of Gore-Tex

All the other features of nylon but also breathable, allows water vapour to escape so it's more comfortable

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

Features of biodegradable plastics

Contain special parts which dissolve easily and break up the polymer chain

Results of a chemical change

New substances are formed


An energy change takes place


The change cannot be easily reversed

Effects of cooking on protein molecules

Irreversible denaturing (changing shape and appearance)

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

Effects of heating on baking powder

Sodium hydrogen carbonate decomposes to make sodium carbonate, water, and carbon dioxide. This carbon dioxide

Write the symbol equation for the heating of baking powder

2NaHCO3 --> Na2CO3 + H2O + CO2

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

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

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.

Where do some cosmetics come from? (2)

Natural resources (lavender, musk and rose)


Manufactured (Synthetic)

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.

Smells are made of ...?

Molecules

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.



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.

Advantages of animal testing for cosmetics

Can prevent humans from being harmed

Disadvantage of animal testing for cosmetics

Cruel to animals


Animals don't have same body chemistry, so test results may not be useful.

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.



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.

What are Colloids?

Small, solid particles that are mixed well (dispersed but not dissolved) with liquid particles. E

Example of a colloid

Paint

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.

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.

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.

What do thermochromic pigments do?

Change colour when they are heated or cooled.

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.

What do Phosphorescent pigments do?

Glow in the dark. They absorb and store energy and releases light when it is dark.

What were the first 'glow in the dark' paints made using?

Radioactive material a pigments and used for things like watches.