Topic 8 - Fuels And Earth Science

Question 1

What are hydrocarbons?

Answer 1

Compounds that contain carbon and hydrogen only

Question 2

What is crude oil?

Answer 2

A complex mixture of hydrocarbons containing molecules in which carbon atoms are in chains or rings.
It’s an important source of useful substances and a finite resource.

Question 3

How is crude oil separated into simpler + more useful mixtures?

Answer 3

By fractional distillation- oil is heated until most has turned into gas. Gases enter fractionating column. In column there’s temperature gradient. Longer hydrocarbons with HBP turn back into liquids + drain out column near bottom. Shorter hydrocarbons turn to liquid + drain out near top where it’s cooler.

Question 4

What are the 6 fractions separated from crude oil?

Answer 4

Gases
Petrol
Kerosene
Diesel oil
Fuel oil
Bitumen

Question 5

What is the acronym for the 6 fractions?

Answer 5

Glamorous People Keep Dogs For Babies

Question 6

What are the uses of gases?

Answer 6

Used in domestic heating + cooking

Question 7

What are the uses of petrol?

Answer 7

Used as a fuel in cars

Question 8

What is the uses of kerosene?

Answer 8

Used as a fuel in aircraft

Question 9

What are the uses of diesel oil?

Answer 9

Used as a fuel in sound cars and larger vehicles eg trains

Question 10

What are the uses of fuel oil?

Answer 10

Used as a fuel for large ships and in some power stations

Question 11

What are the uses of bitumen?

Answer 11

Used to surface roads and roofs

Question 12

What are the properties of shorter hydrocarbons?

Answer 12

Intermolecular forces break a lot more easily therefore have lower BP
Easy to ignite so usually gases at room temp
Low viscosity and are much runnier

Question 13

What are the properties of longer hydrocarbons?

Answer 13

Strong intermolecular forces therefore have high BP
Hard to ignite
Liquids at room temp
High viscosity + thick

Question 14

What is a homologous series?

Answer 14

Series of compounds which have the same general formula. Differ by CH2 in molecular formulae from neighbouring compounds. Show a gradual variation in physical properties. Have similar chemical properties.

Question 15

What do complete combustion reactions of hydrocarbons produce?

Answer 15

Carbon dioxide + water. Energy is given out.

Question 16

Explain what the incomplete combustion of hydrocarbons can produce

Answer 16

Carbon and carbon monoxide due to lack of oxygen.

Question 17

How does carbon monoxide act as a toxic gas?

Answer 17

It can combine with red blood cells + stop your blood from carrying oxygen around the body. This cane lead to fainting, coma or death

Question 18

What are the problems caused by incomplete combustion?

Answer 18

Particles of carbon can be released into atmosphere. When they fall back to ground they deposit themselves as soot on buildings. Reduces air quality leading to respiratory problems.

Question 19

Explain how impurities in some hydrocarbon fuels result in the production of sulfur dioxide

Answer 19

When fossil fuels are burned they release sulfur dioxide (SO2) which comes from the sulfur impurities in the fossil fuels.

Question 20

How is acid rain caused?

Answer 20

When sulfur dioxide mixes with clouds is forms dilute sulfuric acid which falls as acid rain.

Question 21

What are the problems with acid rain?

Answer 21

Causes lakes to become acidic + plants + animals die. Also kills trees and damages limestone buildings

Question 22

What are the non renewable fossil fuels obtained from crude oil?

Answer 22

Petrol, kerosene, diesel oil + methane found in natural gas.

Question 23

Why are nitrogen oxides produced when fuels are burned in engines?

Answer 23

Caused by the internal combustion of engines in cars - nitrogen + oxygen in air react.

Question 24

What is bad about nitrogen oxides being produced from engines?

Answer 24

They’re harmful pollutants - can contribute to acid rain + photochemical smog which is air pollution that can cause breathing difficulties

Question 25

What are the advantages of hydrogen being used instead of petrol in cars?

Answer 25

Very clean Only waste product is water Obtained from water which is renewable

Question 26

What are the disadvantages of using hydrogen instead of petrol in cars?

Answer 26

Need a special expensive engine Expensive to manufacture + uses energy from another source Hard to store + not widely available Very reactive

Question 27

What is cracking?

Answer 27

breaking down of larger, saturated hydrocarbon molecules (alkanes) into smaller, more useful ones, some of which are unsaturated (alkenes)

Question 28

Why is cracking used/necessary?

Answer 28

Lots of the longer molecules produced from fractional distillation are cracked into smaller ones as there’s more demand for products like petrol + diesel than bitumen + fuel oil

Question 29

What formed the earths early atmosphere?

Answer 29

Gases like CO2, steam, methane + ammonia produced by volcanic activity

Question 30

What was the earths early atmosphere thought to contain?

Answer 30

Little/no oxygen as there wasn’t any plants Large amount of CO2 + water vapour from volcanoes erupting Small amounts of other gases (methane + ammonia)

Question 31

How did the condensation of water vapour form oceans?

Answer 31

As the earth started to warm up the water vapour evaporate, cooled + condensed to create clouds which then rained down + formed oceans.

Question 32

How did the amount of CO2 in atmosphere decrease?

Answer 32

Lots of CO2 dissolved into the oceans

Question 33

How did the amount of oxygen in the atmosphere increase?

Answer 33

Primitive plants photosynthesised + removed CO2 + produced oxygen. Oxygen gradually built up and much of the CO2 got locked in fossil fuels + sedimentary rocks.

Question 34

Describe the chemical test for oxygen

Answer 34

Take a glowing splint and place it into a test tube. If it relights oxygen is present.

Question 35

What is the greenhouse effect?

Answer 35

1- earth radiates some heat radiation as infrared radiation (IR) 2- some IR absorbed by greenhouse gases 3- some IR is reflected back to Earth by greenhouse gases 4- some IR is re emitted to space 5- absorption + reflection of IR by greenhouse gases is what keeps Earth warm

Question 36

What are greenhouse gases?

Answer 36

Gases in atmosphere that absorb + reflect heat radiation. Present in small amounts. Carbon dioxide, methane + water vapour are 3 gg