Chemistry - C1

Question 1

Why are fossil fuels finite and non-renewable resources?

Answer 1

• they are finite because they are no longer being made or are being made extremely slowly
• they a non renewable resources as they are being used up faster than they are being formed

Question 2

What is cracking and what does it do?

Answer 2

• cracking helps an oil refinery match its supply of useful products such as petrol with the demand for them.
• cracking converts large alkane molecules into smaller alkane and alkene molecules

Question 3

Explain hydrocarbons and intermolecular forces?

Answer 3

• hydrocarbons with bigger molecules have stronger intermolecular forces between their molecules, and so have higher boiling points than hydrocarbons with smaller molecules

Question 4

What is fractional distillation?

Answer 4

• crude oil can be separated from fractional distillation. It is heated near the bottom of a fractionating column. Fractions with low boiling points ‘exit’ at the top of the tower. There is a temperature gradient between the bottom and top column

Question 5

What are the key factors that need to be considered when choosing a fuel?

Answer 5

• energy value
• availability
• storage
• toxicity
• pollution caused
• ease of use

Question 6

What are the processes in the carbon cycle?

Answer 6

• photosynthesis
• respiration
• combustion

Question 7

Where did the original atmosphere come from?

Answer 7

• the original atmosphere came from the degassing of early volcanoes which were rich in water and carbon dioxide. The water condensed to form oceans. Photosynthetic organisms helped to increase the levels of oxygen through photosynthesis

Question 8

What happens when hydrocarbons burn in plentiful supply of air?

Answer 8

• carbon dioxide and water are made

- in an experiment, carbon dioxide can be tested for with limewater; it turns the limewater milky

Question 9

What does the present day atmosphere contain?

Answer 9

• oxygen: 21%
• nitrogen: 78%
• carbon dioxide: 0.035%

Question 10

What is a hydrocarbon?

Answer 10

• it is a compound of carbon atoms and hydrogen atoms only

Question 11

What are alkanes and alkenes?

Answer 11

• alkanes are hydrocarbons which contain single covalent bonds only
• alkenes are hydrocarbons which contain a double covalent bond between carbon atoms

Question 12

When are addition polymers made?

Answer 12

• they are made when alkene monomer molecules react together under high pressure and with a catalyst

Question 13

Explain plastics and intermolecular forces?

Answer 13

• plastics that have weak intermolecular forces between the polymer can easily be stretched as the polymer molecules can slide over one another. Rigid polymers have cross- linking bridges

Question 14

What is crude oil a mixture of?

Answer 14

• many hydrocarbons

Question 15

What are nylon and goretex?

Answer 15

• nylon and goretex are both polymers with suitable properties for particular uses.
• nylon is tough, lightweight and keeps water and UV light out
• goretex has all these properties but allows water to pass out so that sweat does not condense

Question 16

What do protein molecules do when they are cooked?

Answer 16

• protein molecules in eggs and meat denature when they are cooked
• the change of shape of the protein molecule is permanent

Question 17

What are emulsifiers?

Answer 17

• emulsifiers are molecules with a water-loving (hydrophilic) part and an oil loving (hydrophobic) part. The hydrophilic end bonds to water molecules and the hydrophobic end bonds to oil molecules, keeping the oil an water from separating

Question 18

What are paints and types of paint pigments?

Answer 18

• paints are colloids because the particles are mixed and dispersed throughout a liquid but are not dissolved in it
• thermochromic pigments change colour with heat and are used, for example, in babies toys that are immersed in water to show whether the water is too hot
• phosphorescent pigments glow in the dark and are much safer for use in products than the alternative radioactive substances