Non Renewables - Seneca

Question 1

Why is crude oil a mixture

Answer 1

Crude oil is a mixture of lots of different compounds that are not chemically combined. Most of the compounds in crude oil are hydrocarbons.

Question 2

What property of hydrocarbons can change their properties ?

Answer 2

Hydrocarbons differ in their size, which can change the properties of the hydrocarbon.

Question 3

What are most compounds in crude oil ?

Answer 3

Most compounds are hydrocarbons

Question 4

Where is crude oil found ?

Answer 4

Crude oil is found in rocks and is used to produce fuels and other important chemicals.

Crude oil is made from the fossilised remnants of ancient plankton.

Question 5

Short and long chain hydrocarbons

Answer 5

Hydrocarbons with few carbon atoms are called ‘short-chain hydrocarbons’.

Long-chain hydrocarbons

Hydrocarbons with lots of carbon atoms are called ‘long-chain’ hydrocarbons

Question 6

What are fractions of fractional distillation ?

Answer 6

Fractional distillation is the process of separating crude oil into groups of hydrocarbons with similar numbers of carbon atoms. We call these groups of hydrocarbons “fractions”.

Question 7

Collection of fractions from fractional distillation

Answer 7

Collection

The fractions are collected. They are then processed to create end products:Fuels (e.g. petrol, diesel) are a common end product.The petrochemical industry can use some fractions as feedstock (material used in an industrial process) to make products such as solvents, detergents, lubricants etc.

Question 8

Uses of the fractions of crude oil

Answer 8

Bitumen

Surfacing roads and roofs

Fuel oil

Fuel for ships and power stations

Diesel Oil

Fuel for some cars and trains

Kerosene

Fuel for aircrafts

Gases

Domestic heating and cooking

Petrol

Fuel for cars

Question 9

Where is the temperature highest in a fractional distillation column ?

Answer 9

Fractional distillation works because different sizes of hydrocarbons have different boiling points. At the bottom of the column, where the temperature is highest, long-chain hydrocarbons condense and are collected as liquids.

Question 10

Properties of a homologous series

Answer 10

Physical and chemical properties
The members of the homologous series have similar chemical properties, but the physical properties can change.

For example, as the carbon chain becomes longer, the boiling point increases.

Molecular formulas

The molecular formulas of neighbouring compounds differ by a CH2unit.

Question 11

What Is a homologous series ?

Answer 11

The homologous series is a series of compounds with the same general formula.

Question 12

Three important properties of hydrocarbons

Answer 12

Flammability

Hydrocarbons with longer chains are less flammable.

Boiling point

Hydrocarbons with longer chains have higher boiling points.

Viscosity

Hydrocarbons with longer chains have higher viscosity (i.e. they are thicker and flow less easily).

Question 13

What is cracking of hydrocarbons ?

Answer 13

Thermal decomposition reactions - Cracking is the process that breaks down long-chain hydrocarbons into shorter-chain molecules that are more useful

Question 14

What is steam Cracking?

Answer 14

Vapourised heavy hydrocarbons are mixed with steam in a high temperature environment.The products include alkanes and alkenes.E.g. decane → octane + ethene

Question 15

What is catalytic cracking ?

Answer 15

Vapourised heavy hydrocarbons are passed over the top of a heated catalyst.

Alkanes and alkenes are produced by this reaction.

E.g. hexane → butane + ethene

Question 16

Why does combustion depend on oxygen avaliable ?

Answer 16

The equations for the combustion (burning) of hydrocarbons depend on the amount of oxygen that is available.

Question 17

Problems with incomplete combustion ?

Answer 17

As well as producing carbon monoxide, incomplete combustion produces soot.

Soot can build up in appliances and cause problems. This happens in cars and any items that use carbon compounds as fuel.

Question 18

Combustion burning with plenty of oxygen :

Answer 18

Burning with plenty of oxygen

The combustion (burning) of hydrocarbons when there is a good air supply involve:Energy release.The oxidation of carbon and hydrogen to create carbon dioxide and water.

Question 19

Combustion burning with little oxygen - properties of carbon monoxide.

Answer 19

Burning with a lack of oxygen

If alkanes are burned without enough oxygen, then carbon monoxide can be created:2C + O2→ 2COCarbon monoxide is a gas with the following properties:ColourlessToxicOdourless

Question 20

Impurities in fossil fuels - nitrogen oxides

Answer 20

Nitrogen oxides

When hydrocarbons are burned in a confined space (e.g. in the internal combustion engines of cars), the high temperatures can cause nitrogen and oxygen to react.

This leads to the formation of toxic nitrogen oxides.

Question 21

Sulfur impurities in fossil fuels - contribution to acid rain.

Answer 21

Sulfur is an impurity that is present in all fossil fuels.Sulfur oxidises when burned. This produces the toxic gas sulfur dioxide.If inhaled, sulfur dioxide can cause respiratory (breathing) problems.Sulfur dioxide can react with water to form sulfuric acid, which is a major component (part) of acid rain.Acid rain causes steel corrosion, the weathering of buildings and statues, and the death of insects, plants, and aquatic organisms.

Question 22

Advantages of hydrogen fuel cells over fuels ? (Sometimes in cars)

Answer 22

Advantage - toxicity

Hydrogen fuel cells use hydrogen and oxygen and the only waste product is water.This means no greenhouse gases are emitted. Petrol vehicles emit greenhouse gases into the atmosphere.

Advantage - capacity

Hydrogen fuel cells produce more energy per gram of hydrogen relative to petrol.

Question 23

Disadvantages of hydrogen fuel cells

Answer 23

Disadvantages

But hydrogen has to be stored at a high pressure and hydrogen gas is explosive.There are not many places to refuel either.

Question 24

What are the dangers of acid rain ?

Answer 24

Acid rain causes steel corrosion, the weathering of buildings and statues, and the death of insects, plants, and aquatic organisms.