GCSE Chemistry Flashcards by Gabriel Selaj

Fractional Distallation

Process which separates chemicals in crude oil into useful fractions

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Crude oil

A mixture of comparatively volatile liquid hydrocarbons

Contains nitrogen, sulfur, and oxygen

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Hydrocarbon

Compound of hydrogen and carbon

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Alkaline

Having the properties of an alkali or containing alkali

pH greater than 7

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name the different fractions from crude oil

gasoline

naphtha series

kerosine oil

diesel oil

residual oil

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Gasoline

Mainly used in vehicle engines

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Naptha series

to dilute heavy crude oil to reduce its viscosity

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Kerosene oil

burning in kerosene lamps, domestic heaters, furnaces

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Diesel oil

any liquid fuel specifically designed for use in a diesel engine

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Residual oil

used as a fuel for power generators or ships

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how to separate crude oil into fractions in a school laboratory

Fractional distallation

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Fractional distallation process

heated crude oil enters a tall fractionating column

vapours from the oil rise through the column

vapours condense when they become cool enough

liquids are led out of the column at different heights

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How to classify a hydrocarbon as an alkane

Depending on the presence of double carbon bonds

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state the names and molecular formula the first four alkanes

Methane - CH4

Ethane - C2H6

Propane - C3H8

Butane - C4H10

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Composition of first 4 alkanes

Methane - CH4

Ethane - CH3 - CH3

Propane - CH3-CH2-CH3

Butane - CH3-2(CH2)-CH3

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Describe how the trend in colour, viscosity, flammability and boiling point changes as the length of the hydrocarbon chain changes

How chain length affects

Colour - The greater the number of carbon atoms (chain length), the darker in colour that fraction is

Viscosity - increases as the number of carbon atoms (chain length) increases

Flammability - decreases with increasing molecular size

Boiling point - increases as the number of carbon atoms (chain length) increases

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describe how the properties of a fraction of crude oil make it appropriate for its use

Fractional distillation is used to separate crude oil into simpler, more useful fractions

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How fractional distillation is able to separate crude oil into fractions

Different hydrocarbons have different boiling points

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classify the classification of a chemical as an alkane

Alkanes have the general formula CnH2n+2 can be divided into 3 groups

linear straight-chain alkanes
branched alkanes
cycloalkanes

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justify the classification of a chemical as an alkane

lack of unsaturation

distinct from other compounds that also contain carbon and hydrogen

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explain in detail how fractional distillation is used to separate crude oil into fractions

First crude oil is heated and most of it evaporates

It enters the fractionating column as a gas

As gas rises up the column the crude oil fractions cool and condense out at different levels, depending on their boiling points

Fractions can be used as fuels

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predictions about the properties of crude oil fractions from the fraction’s hydrocarbon chain length

Each crude oil fraction contains a mixture of hydrocarbons

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Properties of crude oil

density

viscosity

boiling point ranges

define complete combustion

happens in the presence of a sufficient amount of oxygen

Combustion

The process of burning something

word equation to describe the complete combustion of a hydrocarbon

Fuel + O2 → CO2 + H2O

word equation to describe the incomplete combustion of a hydrocarbon.

ethane + oxygen → carbon monoxide + carbon + water

Why is complete combustion better than incomplete

Less soot produced More heat produced Carbon monoxide not produced

define the process of cracking

a reaction when larger saturated hydrocarbon molecules are broken down into smaller, more useful hydrocarbon molecules

generate a word equation to describe cracking

CH3 CH2 CH2 CH2 CH2 CH2 CH2 CH3(g)→C 1 CH3 6 CH2 1 Ch3

recognise and give examples of alkenes

Methane propane ethane butane

how to test for the products of complete combustion

First a sample is weighed then burned in a furnace in the presence of excess oxygen All of the carbon is converted to carbon dioxide, and the hydrogen is converted to water in this way

describe a chemical test to show an alkene is present

Bromine water is an orange solution of bromine It becomes colourless when it is shaken with an alkene

justify the use of a given fuel over another

Diesel has a higher energy density than coal

Examples of fuel

wood, coal, biogas, LPG, petrol, diesel

explain in detail how the production of carbon monoxide in incomplete combustion can be lethal

When people are exposed to CO gas, the CO molecules will displace the oxygen in their bodies and lead to poisoning

Balanced symbol equations to calculate products in a combustion reaction

Fuel + O2 → CO2 + H2O

use examples to explain the process of cracking

Cracking is used in the petroleum industry to convert heavy, high-molecular weight fuels into lighter, more valuable products such as gasoline, diesel fuel, and jet fuel

Why is cracking so important to the petrochemical industry

converts larger hydrocarbons into smaller hydrocarbons, the supply of fuels is improved

Similarities between alkenes and alkanes

Both are hydrocarbons Small alkane molecules and small alkene molecules are gases at room temperature Both are nonpolar molecules Both insoluble in water

Differences between alkanes and alkenes

Alkanes contain only single covalent bonds | alkenes have at least 1 double carbon-carbon bond Alkanes are saturated hydrocarbons alkenes are unsaturated hydrocarbons Alkanes exhibit lower reactivity than alkenes

reaction between bromine water and an alkene

Colourless There is no change when bromine water is mixed with an alkane, but it turns colourless when mixed with an alkene

predictions about the properties of crude oil fractions from the fraction’s hydrocarbon chain length

Properties will result in smaller chain lengths

Formation of crude oil

Formed over millions of years from the remains of tiny ancient sea animals and plants

Balanced symbol equations for cracking of alkenes

Composition of crude oil

Complex mixture of hydrocarbons

what is meant by the formula 𝐶𝑛 𝐻2𝑛+2

Alkane is a saturated hydrocarbon that has Carbon-Carbon and Carbon-Hydrogen atoms that are only connected through single bonds

covalent bonds in alkanes

single covalent bonds between carbon atoms

represent alkanes by their chemical formula/molecular formula, structural or displayed formula

CnH2n+2

describe the cultural, economic and environmental impact of the oil industry around the world

Cultural - composes space and shapes culture Economic - responsible for 12.3 million jobs at the start of this year Environmental - damage soils and vegetation directly, and eventually groundwater

Environmental impacts of combustion fossil fuels

release nitrogen oxides into the atmosphere, which contribute to the formation of acid rain

stoichiometric calculations for combustion of fuels

H2 + ½ [O2 + 3.76N2] → H2O + 1.88N2

how to test for unsaturation

Dissolve it in 2ml of distilled water Add bromine water dropwise with constant shaking The given organic compound is unsaturated if the orange color of Bromine disappears

Crude oil renewable or non-renewable

Non-renewable

Where is crude oil found

ROCKS

What is molecule made or

Atoms joined together

Incomplete combustion

when there is an insufficient amount of oxygen supply