4(b) Crude oil

what is crude oil?

a mixture of different hydrocarbons called fractions

describe the process of fractional distillation

1. the crude oil is heated and vaporises

2. the vapours of the hydrocarbons enter a fractionating column which has a temperature gradient (hotter at the bottom, cooler at the top)

3. the hydrocarbons with high boiling points condense at the bottom

4. hydrocarbons with low boiling points rise up the column and condense gradually at different points as they reach their boiling points, which separates them

what are the main fractions of crude oil?

what are their functions?

refinery gases - cooking, domestic heating

gasoline - car fuel

kerosene - plane fuel

diesel - truck and car fuel

fuel oil - ship fuel, power stations

bitumen - road surfacing

define a fuel

a substance that, when combusted, releases thermal energy

what are two nitrous oxides?

how is are nitrous oxides formed?

NO and NO₂

nitrogen and oxygen react in the high pressure and temperature environments of internal combustion engines and blast furnaces

what are some of the adverse effects of nitrogen oxides? (3)

acid rain

they produce photochemical smog

cause breathing difficulties (especially for people with asthma)

what is the formula for sulfur dioxide?

how is sulfur dioxide formed?

what is the symbol equation for the formation of sulfur dioxide?

SO₂

fossil fuels are often contaminated with small amounts of sulfur impurities

when they are burned, the sulfur oxidises into sulfur dioxide

S_(s) + O_{2 (g)} → SO_{2 (g)}

how is acid rain formed from sulfur dioxide?

how is acid rain formed from nitrogen dioxide?

(give equations too)

sulfur dioxide dissolves in rainwater to form sulfuric acid

2 SO_{2 (g)} + O_{2 (g)} + 2 H₂O_(l) → 2 H₂SO_{4 (aq)}

nitrogen dioxide reacts with rainwater to form a mixture of nitrous and nitric acids

2 NO_{2 (g)} + H₂O _(l) → HNO_{2 (aq)} + HNO_{3 (aq)}

4 NO_{2 (g)} + 2 H₂O_(l) + O_{2 (g)} → 4HNO_{3 (aq)}

these droplets get larger and fall as acid rain

what harm can acid rain cause? (4)

corrosion to metal structures, buildings, and statues made of carbonate rocks (e.g. CaCO₃)

hurt aquatic organisms

pollutes crops and water supplies

irritates lungs, throats, and eyes