C1: Carbon Chemistry

Question 1

Describe the cracking of liquid paraffin (petrol).

Answer 1

1. High temperature and catalyst required. 2. Larger hydrocarbon molecules split up into smaller ones. 3. This makes more petrol in higher demand

Question 2

When can crude oil be separated through fractional distillation?

Answer 2

The larger the hydrocarbon molecules, the more energy that is required to overcome the intermolecular forces between these molecules. As a result, similar-sized molecules have similar boiling points; this is why they exit the distillation column at the height.

Question 3

What catalyst is used in cracking?

Answer 3

Aluminium Oxide.

Question 4

What two extra products can be produced as a result of incomplete combustion?

Answer 4

Carbon monoxide and carbon.

Question 5

What is the word equation for complete combustion?

Answer 5

hydrocarbon+oxygen–>carbon dioxide+water

Question 6

Name 3 stages in the evolution of the atmosphere.

Answer 6

1. Volcanoes gave out water vapour and CO2 2. Green plants evolved and produced oxygen 3. Ozone layer allows evolution of complex animals

Question 7

Describe the chemical composition of our atmosphere.

Answer 7

78% Nitrogen 21% Oxygen 0.04% Carbon Dioxide

Question 8

As the Earth evolved, how did nitrogen gas begin to fill the atmosphere?

Answer 8

Firstly ammonia released from volcanoes and reacted with oxygen to produce nitrogen. Secondly, denitrifying bacteria convert nitrates in the ground to nitrogen gas. Nitrogen is an unreactive gas so as it was produced, it wasn’t consumed.

Question 9

Oxygen put into the atmosphere helped create the ozone layer. Why is the ozone layer important for life on Earth?

Answer 9

It blocks out harmful rays from the sun and enabled more complex organisms to evolve.

Question 10

Describe the carbon cycle.

Answer 10

Carbon dioxide is put into the atmosphere though combustion, respiration and decay. Carbon dioxide is removed from the atmosphere via photosynthesising plants.

Question 11

How is acid rain caused?

Answer 11

The combustion of fossil fuels with sulfur impurities leads to sulfur dioxide being put into the air. Furthermore, combustion causes oxygen and nitrogen to react - releasing oxides of nitrogen into the air.

Question 12

How is photochemical smog caused?

Answer 12

Oxides of nitrogen combine with oxygen in the air to produce ozone (O3). Ozone caused breathing difficulties, head aches and tiredness.

Question 13

What is the balanced symbol equation for catalytic conversion?

Answer 13

2CO+2NO–>N2+2CO2

Question 14

Why does cooking mean potatoes are easier to digest?

Answer 14

Potato cells are surrounded by a rigid cell wall made up of cellulars. Humans can’t digest cellulars, so we cook potatoes to rupture their cell walls. The starch grains in the potato also swell up making the potato softer and therefore easier to digest.

Question 15

What is the symbol equation for the thermal decomposition of sodium hydrogen carbonate?

Answer 15

NaHCO3–>Na2CO3+CO2+H2O

Question 16

How do emulsifiers help water and oil to mix? (to make and emulsion)

Answer 16

The emulsifier has a hydrophilic head and hydrophobic tail. The hydrophilic end bonds to water molecules and the hydrophobic tail bonds to oil molecules.

Question 17

What is the word equation for making an ester?

Answer 17

carboxylic acid + alcohol –> ester + water

Question 18

Name 5 properties needed by perfumes.

Answer 18

1. Easily Evaporates or volatile 2. Non toxic 3. Does not react with water 4. Doesn’t irritate skin 5. Insoluble in water

Question 19

What is a solute and what is a solvent?

Answer 19

Solute: substance that is being dissolved Solvent: liquid the solute is being dissolved in

Question 20

Nail varnish does not dissolve in water. Why is this?

Answer 20

1. The attraction between nail varnish molecules is greater than the attraction between the nail varnish molecules and water molecules. 2. The attraction between water molecules is stronger than the attraction between the water molecules and the nail varnish molecules.

Question 21

How does oil paint dry?

Answer 21

The solvent evaporates and then the oil is oxidised by the oxygen in the air, forming a hard film.

Question 22

How do emulsion paints dry?

Answer 22

The water based emulsion dries when the solvent evaporates, leaving behind the binding medium and pigment as a thin solid film.

Question 23

What determines how stretchy or bendy a polymer will be?

Answer 23

If there are weaker intermolecular forces between the polymer chains, the chains are free to slide over each other and can therefore be stretched more easily.

Question 24

Explain how Gore-Tex is a breathable material?

Answer 24

1. Gore-Tex is made up of a layer of expanded PTFE that is attached onto another fabric, such as nylon, to make it stronger 2. The PTFE is a micro porous membrane made up of lots of tiny holes 3. The pores are big enough to allow water vapour to exit, but too small to allow water droplets to enter. Hence breathable and water proof.

Question 25

Describe the bonding in an alkane molecule.

Answer 25

Electrons are shared between multiple hydrocarbon atoms in an alkane. This is called covalent bonding.

Question 26

Why do alkenes decolourise bromine water?

Answer 26

An alkene is an unsaturated compound, meaning it has double bonds available. As a result, an addition polymerisation reaction can occur between the bromine water and the alkene. The result of this is a new colourless solution.

Question 27

As the size of the hydrocarbon molecule increases, how do it’s properties change?

Answer 27

1. It’s boiling point increases 2. It gets less flammable 3. It gets more vicious 4. It gets less volatile

Question 28

LPG exits at the top of the distillation column. What is LPG made up of?

Answer 28

Mostly propane and butane.

Question 29

What is produced as a result of cracking large alkane molecules?

Answer 29

Smaller alkane molecules AND smaller alkene molecules.

Question 30

Why are perfumes volatile?

Answer 30

1. Weak forces of attraction between the particles in liquid perfume 2. Not much energy needed to overcome those weak forces 3. Therefore perfume easily evaporates 4. Hence, it is volatile

Question 31

Why won’t the components of a colloid separate?

Answer 31

The particles are extremely small and evenly dispersed within the solution. As a result, forces of attraction can’t cause the particles to group up and separate out from the solution.

Question 32

How can thermo chromic pigments be given an even greater range of colour changes?

Answer 32

We can combine acrylic paints with thermo chromic pigments to produce paints that change to a variety of colours when the temperature changes.