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Chemistry Year 11 IGCSE > 4.1-4.4. - Organic part 1 > Flashcards

4.1-4.4. - Organic part 1 Flashcards

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1
Q

What can organic compounds exist as?

A

Chains, branched chains or rings of carbon atoms with hydrogen attached.

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2
Q

What are hydrocarbons?

A

The simplest organic compounds are hydrocarbons. These molecules contains carbon and hydrogen only

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3
Q

What is Empirical formula?

A

Simples whole number ratio of atoms in a compound that can be calculated

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4
Q

What is the Molecular formula?

A

Molecular formula counts the actual number of each type of atom present in a molecule.

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5
Q

What is Structual formula?

A

Shows how the atoms in a molecule are joined together

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6
Q

What is Displayed formula?

A

Displayed formula shows all the bonds in the molecule as lines each line represents a pair of shared electrons in a covalent bond

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7
Q

How many carbon chains does each code letter has?

A

Meth - 1
Eth - 2
Prop - 3
But - 4
Pent - 5
Hex - 6

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8
Q

What are Alkanes?

A

Alkanes are a homologous series of similar hydrocarbons in which all the carbons are joined to each other with single covalent bond coded with a ‘ana’ ethane is 2 carbon chain.

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9
Q

What are Alkenes?

A

Alkenes are a homologous series of hydrocarbons which contain carbon- carbon double bond why their name ends in ‘ene’.

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10
Q

What are Isomers?

A

Molecules with the same molecular formula but different structual formula

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11
Q

What is Combustion?

A

Combustion burning that involves a reaction with oxygen.
Combustion of hydrocarbons in excess oxygen gives rise to carbon dioixde and water with the release of a large amount of heat energy like:

Propane burning: C3H8 + 5O2 > 3CO2 +4H20

Butene burning C4H8 + 6O2 > 4CO2 +4H20

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12
Q

What is a Substitution reaction?

A

A substitution reaction occours when an atom or group of atoms s replaced by a different atom or group of atoms for example:

CH3CH3 +Br2 > CH3CH2Br +HBr

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13
Q

What is an Addition reaction?

A

In an addition reaction something is added to a molecule without taking anything away. Alkenes undergo addition reaction like:

CH2CH2 + Br2 > CH2BrCH2Br

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14
Q

What is Crude Oil?

A

When plants and animals living in the sea died and fell to the bottom. Layers of sediment formed on top of them. They formed limestone. The soft tissues was changed by heat and high pressure into crude oil. Crude oil is a finite non renewable resource it can’t be replaced.

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15
Q

What is the structure of Crude oil?

A

Crude Oil is a mixture of hydrocarbons compounds containing carbon and hydrogen only many different hydrocarbons of various sizes in crude oil.

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16
Q

How do the properties of Crude Oil change with the size of the molecule?

A

As the number of carbon atoms in hydrocarbon molecule increases physical properties change.

As the molecules becomes bigger the intermolecular forces of attraction become stronger and it becomes harder to pull molecules away

Boiling point increases the larger the molecule the high the boiling point molecules are attracted to each other more strongly than the smaller ones. More energy required to break these stronger intermolecular forces of attraction.

Liquids becomes less volatile the bigger the hydrocarbon the more it slowly evaporates at RT. This is against because the bigger molecules are strongly attracted and are less likely to turn to a gas.

Liquids become more viscous and flow less easily liquids containing small hydrocarbons molecules are runny. Those containing large molecules flow less easily because of the stronger forces of attraction between their molecules liquids become a darker colour.

Bigger hydrocarbons burn less easily limiting their uses

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17
Q

Why is Crude Oil seperated?

A

Crude oil has no uses so has to be separated into fractions before being used. Fractions are all mixtures each one contains a narrow range of sizes and hydrocarbons with similar boiling points.

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18
Q

What is fractional distillation?

A

Crude oil is heated until it boils and the vapour passes into a fractionating column which is cooler at the top and hotter at the bottom. Vapour rises up the column. The tempreture at the bottom of the column is a lot higher so the hydrocarbons remains a gas at the bottom and as it travels up the column the tempreture of the column becomes lower. When the tempreture falls the hydrocarbons will turn into a liquid.
Smaller molecules have lower boiling points and get further up the column before they condense. Longer chain hydrocarbons have higher boiling points and condense lower down the column so the crude oil is split into fractions.

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19
Q

What are some of the uses of crude oil?

A
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20
Q

What is incomplete combustion?

A

If there is not enough oxygen for hydrocarbons to burn incomplete combustion will occour leads to the formation of carbon monoxide.
Formation of carbon monoxide from the incomplete combustion of hydrocarbons is dangerous it is a colourless and odourless gas very poisonous it reduces the ability of the blood to carry oxygen around the body making possibly ill.

21
Q

What are the environmental problems with burning fossil fuels from Crude Oil?

A

Major environmental problems associated with the burning of fossil fuels derived from Crude oil. Carbon dioixde produced. Can lead to climate change.

Acid rain is formed when water and oxygen in the atmosphere react with sulfur dioxide to produce sulfuric acid or to produce nitric acid and mainly comes from power stations burning fossil fuels.

Acid rain major problem because of the effects on trees and life in lakes it kills trees and fish in the lake and it is so acidic it won’t support life in some lakes.

22
Q

What is the solution to acid rain?

A

The solution to acid rain involves removing sulfur from fuels scrubbing the gases from power stations and factories to remove the SO2

23
Q

What is cracking?

A

Some of the fractions produced in fuel oil are more useful than others.

Cracking is a process in which long chain alkanes are converted into alkenes and shorter chain alkanes the big hydrocarbon molecule in fuel oil can be broken down for the one needed for petrol.

24
Q

What is catalytic cracking?

A

The fuel oil fraction is heated to give a gas and then passed over catalyst silicon dioixde at 600 - 700oc. Higher temp without catalyst.
Cracking is an example of thermal decomposition a big molecule spitting into smaller ones on heating many hydrocarbons found in crude oil have single bonds between the carbon atoms.
C-C bonds are broken and new C=C double bonds are formed.
Cracking produces a mixture of alkanes and alkenes.

25
Q

Why do Oil companies carry out cracking?

A

To produce more petrol
To produce more alkenes that can be used to make polymers

26
Q

What are the alkanes?

A

Simplest family of saturated hydrocarbons. Many of the alkanes are used as fuels. Methane is the major component of natural gas and ethane and propane as well.

27
Q

What is the structual formula of the alkanes?

A

Methane - CH4
Ethane - CH3CH3
Propane - CH3CH2CH3
Butane - CH3CH2CH2CH3
Pentane - CH3CH2CH2CH2CH3

28
Q

What is the molecular and displayed formula of the alkanes?

A
29
Q

What is a homologous series of the alkanes?

A

The alkanes form a homologous series.
They have the same functional group
Similar chemical properties
Show trends in physical properties
Can be described by the same general formula
differ by -CH2- unit
The Alkanes form the simplest homologous series. The alkanes do not have a functional group as they just contain single C-C and C-H bonds are the basis of organic compounds

30
Q

What is the general formula of the alkanes?

A

CNH2N+2

31
Q

What are the series in trends in physical properties of the alkanes?

A

The first four alkanes are gases at room tempreture all the other alkanes are liquids.
The molecule of a homologous series increase in size in a regular way te boiling point increases in a regular way.

As the molecule becomes bigger the strength of the intermolecular forces f attraction increase more energy is required to break the attractions between one molecule One effect of this is boiling point increases in a regular way.

32
Q

What are the similar Chemical properties of the alkane homogolus series?

A

Chemical properties are dependent on the functional group and boiling point within the molecules. Because alkanes only contain carbon carbon single bonds and hydrogen single bonds they all behave in the same way.

33
Q

How does combustion occour in alkanes?

A

All alkenes burn in air or oxygen. If there is enough oxygen, they burn completely to give carbon dioxide and water

CH4 + 202 > CO2 +2H20

If there is not enough oxygen there is incomplete combustion of the hydrocarbon carbon monoxide and carbon soot are obtained.

2C2H6 + 5O2 > 4CO +6H20

34
Q

How do substitution reaction occour in Alkanes?

A

Alkanes react with halogens in the presence of ultraviolet radiation from sunlight. A hydrogen atom in the alkane is replaced by a halogen atom. Known as a substitution reaction one atom has been replaced. For example:

A mixture of methane and bromine as is orange because of the presence of bromine if it is exposed to sunlight it loses its colour and a mixture of bromoethane and hydrogen bromide gases is formed.

CH4 + Br2 > CH3Br + HBr

35
Q

What is Mono - Substitution?

A

This occours when only one hydrogen atom in the alkanes is replaced by a halogen atom.

36
Q

What are the alkenes?

A

The alkenes are a homologous series of hydrocarbons which contain carbon carbon double bonds C=C . The C=C bond is the functional group of the alkenes

37
Q

What are the names of the 3 alkenes?

A

Ethene
Propene
But-1-ene

38
Q

What is the molecular formula of the alkenes?

A

Ethene - C2H4
Propene - C3H6
But-1-ene - C4H8

39
Q

What is the empirical formula of the alkenes?

A

Ethene - CH2
Propene - CH2
But-1-ene - CH2

40
Q

What is the structual formula of the alkenes?

A

Ethene - CH2=CH2
Propene - CH2= CHCH3
But-1-ene - CH2=CHCH2CH3

41
Q

What is the displayed the formula of the alkenes?

A
42
Q

What are unsaturated hydrocarbons?

A

Alkenes are unsaturated compounds because they contain C=C double bonds. A saturated compound contain single C-C

43
Q

What is the general formula of the alkenes?

A

CNH2N

44
Q

What are the physical properties of the alkenes?

A

Very similar to those of the alkanes. Small alkanes with up to four carbon atoms are gases at room temp/

45
Q

What are the chemical reactions of the alkenes?

A

Alkenes burn in air or oxygen to give carbon dioxide and water
C2H4 + 302 > 2CO2 + 2H20

46
Q

How does addition occour in the alkenes?

A

The C=C double bond is the functional group. The functional group determines the Chemical properties of a compound. Alkenes have characteristic chemical properties which are very different to those of Alkanes. Alkenes much more reactive.

Alkenes undergo addition reactions part of the double bond breaks to become a single C-C bond and the electrons are used to join other atoms onto the two carbon atoms.

47
Q

Why is bromine added to Alkenes?

A

They are used to make polymers and are the starting material for other chemicals

Bromine added to alkenes no need for heat light or catalyst. Use bromine water
Bromine water is orange and a product of 1,2 - dibromoethane is a colourless liquid.

CH2=CH2 + Br2 > CH2BrCH2Br

48
Q

How to test for a unsaturated compound?

A

Any compound with carbon-arbon double bonds reacts with bromine in a similar way to ethene. This is used to test for a carbon double bond. if shake an unknown organic compound with bromine water and the orange bromine water is decourlised the compound contains carbon carbon double bonds. If it is a gas bubble it through bromine water.

Chemistry Year 11 IGCSE (20 decks)

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