Jacob S5 Chem 20251217 - fossil fuels

fractional distillation of petrol, greenhouse effect, car exhaust, catalytic converter

What physical property is used to separate petroleum into fractions?

The different boiling points of different compounds.

Why does each collected fraction have a boiling point range, rather than a single fixed point?

Each fraction is a mixture of compounds.

What happens to petroleum when it is heated in the fractionating column?

It vaporises.

Why do molecules with smaller molecular size have lower boiling points?

Van der Waals’ forces between smaller molecules are weaker.

Where in the fractionating tower do molecules with lower temperatures of condensation condense?

At the higher part which has lower temperature.

Where do molecules with larger molecular size condense in the fractionating tower?

At the lower part which has higher temperature.

What is the purpose of the mineral wool in the simple lab distillation setup (Figure 1)?

To avoid spilling if the apparatus is mishandled during assembly.

What is the function of the cold water in the simple lab setup?

To condense the various fractions obtained in the process.

What is the position of the thermometer designed to measure in the lab setup?

The boiling points of the fraction coming out.

Which collected portion in the simple distillation setup has the lowest boiling point?

The portion collected in the first tube.

What specific component in the complex lab setup cools the vapour?

Condenser.

What is added to the crude oil to prevent uneven heating?

Anti-bumping granules/stones.

What is the catalyst material in a catalytic converter often supported on?

A ceramic block.

What is the colour of the fraction boiling above 250°

Brown.

Describe the flammability of the fraction with a boiling point between 40° and 170°.

High.

How does the viscosity of the 40° – 170° fraction compare to the higher boiling fraction?

Low.

What property is low for the fraction boiling above 250°

Volatility.

Describe the flame produced by the 40° – 170° fraction.

Yellow and not sooty.

Which fraction has a higher relative molecular mass of its molecules?

The fraction with boiling point above 250°.

Why is petrol considered more volatile than diesel oil?

Van der Waals’ force between smaller molecules or weaker.

Why is petrol less sooty than diesel oil upon burning?

It has lower carbon content.

Why does petrol undergo complete combustion easily?

Molecules of petrol have a shorter carbon chain.

What radiation is trapped by carbon dioxide, causing the Earth to warm?

Infrared radiation.

What is the high energy radiation that passes through the atmosphere to warm the Earth surface?

Radiation from the Sun.

What overall effect is enhanced by burning fossil fuels?

Greenhouse effects.

Name one consequence of global warming that affects crop production.

Affecting global weather.

What is the result of polar icecaps melting due to global warming?

Low-lying areas will flood.

Besides text CO2 and Methane, name one major greenhouse gas (other than Ozone, water vapour or CFCs).

Nitrogen oxide NOx

What is one primary reason for the rapid increase in motor vehicle text CO2 emissions?

Large quantities of petrol or diesel oil are burnt.

What factor leading to deforestation contributes to increased text CO2?

Rapid growth in population needs more land for housing.

Name one source for the increase in Methane concentration besides rice paddies.

Cattle.

How can methane be used to prevent its increase in the atmosphere?

Methane from biomass can be used as fuel.

Name one alternative source of energy (not solar or methane) that can generate electricity instead of fossil fuels.

Nuclear energy/wind energy.

What toxic gas is produced from the incomplete combustion of petrol?

Carbon Monoxide ( CO}).

What gas is produced by the complete combustion of petrol?

Carbon dioxide ( CO2).

What chemical in the body does CO} combine with, stopping oxygen carriage?

Haemoglobin.

What is the term for the product of incomplete combustion that appears as dark smoke?

Suspended particles (mainly C particles).

SO2 is formed from the combustion of what impurities in fossil fuels?

Sulphur.

Besides SO2, what other pollutant released from combustion irritates the respiratory system?

NOx.

What reaction causes N2 to react with O2 to form Nitrogen oxide (NOx)?

High temperature in the car engine.

What specific type of smog is caused by NOx?

Photochemical smog.

How do unburnt hydrocarbons exit the car?

Petrol escape in the car exhaust.

What is the primary health risk associated with unburnt hydrocarbons?

It is carcinogenic.

Name one effect of acid rain on vegetation.

Can damage to plants.

V. Pollution Reduction Technology

What specific catalyst materials are possible for a catalytic converter?

Platinum (Pt), Rhodium (Rh).

What type of fuel must be used with a catalytic converter?

Unleaded petrol.

Why is lead compound usage prohibited with catalytic converters?

Lead compound or lead poisons the catalyst.

Name one gas that passes through the catalytic converter without chemical change.

CO2/ N2/ H2O.

What is the technique used by power stations (using scrubbers) to reduce SO2 emission?

Neutralisation.

What device do power stations use to reduce the emission of particulates (mainly C particles)?

Electrostatic precipitator.

Name one facility (besides factories) that is a source of air pollutants.

Incinerators/Power station.

What is one alternative fuel type listed for reducing car exhaust pollution?

Using liquefied petroleum gases.

What is the purpose of the catalyst being in a network of fine tubes?

Such a form increases the surface area of the catalyst.

What action is necessary to prevent excess black smoke emission from cars?

Regular checking of car exhaust system.