Organic Chemistry

Question 1

What is cracking

Answer 1

Heating longer chains of hydrocarbon to make shorter chains

Question 2

What is an isomer

Answer 2

Molecules with the same molecular formula but different structural formula

Question 3

What is an unsaturated molecule

Answer 3

Molecules that contain one or more double bonds

Question 4

Wht is a saturated molecules

Answer 4

Hydrocarbons that contain only single bonds between carbon atoms

Question 5

What is the formula for complete combustion

Answer 5

Hydrocarbon+oxygen> carbon dioxide + water

Question 6

What are the products of incomplete combustion and their faults

Answer 6

Carbon monoxide- binds to the haemoglobin in the blood where oxygen is meant to bind, leading to fainting, coma or death. It is colourless and odorless

Particulates/soot- Leads to global dimming, and respiratory problems if inhaled

Question 7

What is the bromine water test

Answer 7

The bromine water test is use to identify between saturated (alkanes) and unsaturated (alkenes) hydrocarbons.

Add orange bromine water to the hydrocarbon sample and shake the test tube gently.

Alkanes do not react so if the solution stays orange, it is saturated (alkane).

If the solution turns colourless, alkenes are present and the molecule is unsaturated

Question 8

Is an alkane saturated or unsaturated

Answer 8

Saturated (single bonds)

Question 9

Is an alkene saturated or unsaturated

Answer 9

Unsaturated (double bonds)

Question 10

what is the homologous series

Answer 10

A series of organic compounds that have the same general formula and similar chemical properties.
These include:
alkanes
alkenes
alcohols
carboxylic acids

Question 11

What are the two types of cracking

Answer 11

Catalytic cracking
Steam cracking

Question 12

Explain catalytic cracking

Answer 12

The hydrocarbon is heated until it’s vaporised (a gas).

Put the gas in contact with the catalyst (hot powdered aluminium oxide)

Question 13

Explain steam cracking

Answer 13

Heat the hydrocarbon to make it a gas then heat again at very high temperatures causing the chains to break down

Question 14

What’s the word equation for cracking

Answer 14

Long chain alkane > shorter alkane + Alkene

Question 15

What do we do with the alkenes that are formed from cracking

Answer 15

We can use them to form polymers and can use them to produce other chemicals

Question 16

What is a cation

Answer 16

A positively charged ion

Question 17

Are cations usually metals or non metals and what is the one exception

Answer 17

They are usually metals as metals form positive ions.
Ammonium ion NH4 is a non metal cation.

Question 18

What are the two groups of tests for cations

Answer 18

The flame tests
The metal hydroxide tests

Question 19

Describe the flame test

Answer 19

Take a platinum wire loop and clean it by dipping it in some dilute hydrochloric acid, rinsing it in distilled water and heating it over a bunsen burner flame.

Dip the wire loop in the compound you want to test.

Hold the loop wire in the clear part of the blue flame (this is the hottest part).

See what colour the flame turns as the compound burns.

Question 20

What colour does lithium ions turn when burning

Answer 20

red

Question 21

What colour does sodium ions turn when burning

Answer 21

yellow

Question 22

What colour does potassium ions turn when burning

Answer 22

lilac

Question 23

What colour does calcium ions turn when burning

Answer 23

orange/red

Question 24

What colour does copper ions turn when burning

Answer 24

green/blue

Question 25

What is a limitation of the flame test

Answer 25

If you have two or more different metals in your sample, then the colours will mix together so you won’t be able to tell which metals you have.

Question 26

What is the metal hydroxide test

Answer 26

We react metals with a solution of sodium hydroxide and see what colour the solution turns. This is possible because some metal ions form coloured precipitates when reacting with hydroxide ions

Question 27

When reacting with sodium hydroxide what colour does copper form

Answer 27

Blue colour. (copper hydroxide is formed and a blue colour is seen.)

Question 28

When reacting with sodium hydroxide what colour does calcium form

Answer 28

white precipitate

Question 29

When reacting with sodium hydroxide what colour does iron form

Answer 29

Green precipitate

Question 30

When reacting with sodium hydroxide what colour does iron (FE3+) form

Answer 30

brown precipitate

Question 31

When reacting with sodium hydroxide what colour does magnesium form

Answer 31

white precipitate

Question 32

When reacting with sodium hydroxide what colour does aluminium form

Answer 32

forms a white precipitate but if there is excess it redissolves to form colourless solution

Question 33

What is an anion

Answer 33

A negatively charged ion

Question 34

What is the carbon dioxide test

Answer 34

Put the gas in a test tube and connect it using a rubber tube to another test tube of limewater. If it turns cloudy carbon dioxide is present

Question 35

What is the test for sulfphates

Answer 35

Add dilute hydrochloric acid to the test tube and add barium ions. If a white precipitate is seen, sulphur is present

Question 36

What is the test for halide ions

Answer 36

Add dilute nitric acid. to remove impurities Add silver nitrate. If it reacts with chloride ions a white precipitate is formed If it reacts with bromide ions a cream precipitate is formed If it reacts with iodide ions a yellow precipitate is formed

Question 37

Why use flame photometry

Answer 37

It can detect individual wavelengths that are emitted from different ions The intensity of the line on the spectrum indicates the concentration of the ion If a sample contains different ions the spectrum will show lines for all of them Very accurate very fast

Question 38

As the length of the carbon chain in alkanes increases, what happens to the boiling point

Answer 38

Increases

Question 39

Longer alkanes with more than 4 carbons are what state at room temperature

Answer 39

liquids

Question 40

As the chain (number of carbons) increases in alkanes do they become more or less viscous

Answer 40

More viscous (sticky and thick)

Question 41

As the chain (number of carbons) increases in alkanes do they become more or less volatile

Answer 41

less volatile (how easy it is to evaporate)

Question 42

Shorter alkanes are easy to burn, they are more..

Answer 42

flammable

Question 43

shorter alkanes are great for

Answer 43

fuels

Question 44

What does the carbon carbon double bond in an alkene do

Answer 44

Allows Addition reactions to take place. Opens up allowing atoms of another molecule to bond with the carbon

Question 45

What is the functional group for alcohol

Answer 45

-OH (hydroxyl)

Question 46

Alcohols burn in oxygen to form what

Answer 46

CO2 and H2O

Question 47

What are two properties of alcohol

Answer 47

soluble in water Used as fuels, solvents, and in alcoholic drinks

Question 48

How is ethanol produced

Answer 48

Fermentation. Hydration of ethene (ethene +steam)

Question 49

what is the functional group of carboxylic acids

Answer 49

-COOH

Question 50

properties of carboxylic acids

Answer 50

Weak acids (do not fully ionise in water) react with carbonates to produce CO2 salt and water React with alcohols to form esters

Question 51

What is condensation polymerisation

Answer 51

When monomers join and produce a smaller molecule like water

Question 52

What is addition polymerisation

Answer 52

When monomers join to form polymers

Question 53

What is hydrogenation

Answer 53

Where hydrogen is added to an unsaturated compound, like an alkene to convert it into a saturated compound

Question 54

What two conditions are needed for fermentation

Answer 54

Warm temp of 25-40 sterile conditions