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Organic Chemistry Flashcards

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1
Q

What is the general formula for alkanes?

A

-C nH2n+2
​

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2
Q

Name the first four alkanes in the homologous series.

A

-methane (CH₄), ethane (C₂H₆), propane (C₃H₈), and butane (C₄H₁₀).

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3
Q

What is fractional distillation used for?

A
  • to separate the different hydrocarbons in crude oil into fractions, each containing molecules with a similar number of carbon atoms.
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4
Q

What are the main fuels produced from crude oil?

A

-petrol, diesel oil, kerosene, heavy fuel oil, and liquefied petroleum gases (LPG).

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5
Q

What products are made by the petrochemical industry from crude oil?

A

-solvents, lubricants, polymers, and detergents.

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6
Q

What is the result of the complete combustion of a hydrocarbon?

A
  • carbon dioxide (CO₂) and water (H₂O), along with energy.
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7
Q

What is cracking

A
  • the process of breaking down large hydrocarbons into smaller, more useful molecules like alkanes and alkenes.
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8
Q

How are alkenes different from alkanes?

A

-Alkenes are more reactive than alkanes because they contain at least one double bond between carbon atoms.

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9
Q

What are the two main methods of cracking hydrocarbons?

A

-catalytic cracking and steam cracking.

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10
Q

What are alkenes used for?

A

-to produce polymers and as starting materials for the production of many other chemicals.

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11
Q

What are hydrocarbons?

A

-molecules made up of hydrogen and carbon atoms only

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12
Q

how is crude oil formed?

A
  • it is formed over millions of years from the remains of sea creatures called plankton which were buried in mud.
    -it is a mixture of molecules called hydrocarbons
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13
Q

what does viscosity tell us?

A

-the thickness of a fluid
-longer hydrocarbon molecules have higher viscosity while shorter hydrocarbons have lower viscosity

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14
Q

what does flammability tell us?

A

-how easily a hydrocarbon combusts (burns)
-short chain hydrocarbons are extremely flammable

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15
Q

what does boiling point tell us?

A

-the temperature a liquid turns into a gas.
-short chain hydrocarbons have low boiling points while long chain carbons have high boiling points

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16
Q

what are the steps of fractional distillations?

A

-firstly, the crude oil is heated at a very high temperature
-this causes the crude oil to boil - all of the hydrocarbons evaporate and turn into gas
-the crude oil vapour is now fed into the fractional distillation column
-the column is hotter at the bottom and cooler the top
-the hydrocarbon vapours now rises up the column and condenses at their boiling points
-the liquid fraction is then removed
-the remaining hydrocarbon fuels condense continue rising up the column and condense at their own boiling points.

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17
Q

key point for fractional distillation process

A

-very long chain hydrocarbons have very high boiling points that are removed from the bottom of the column
-very short chain hydrocarbons have very low boiling points and these do not condense and are removed from the top of the column as gases.

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18
Q

how are fractions used for the petrochemical industry?

A

-as feedstock which is a chemical that is used to make other chemicals

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19
Q

why do long chain hydrocarbons not make good fuels?

A

-they are not very flammable

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20
Q

what are the conditions required for catalytic cracking?

A

-high temperature and a catalyst

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21
Q

what are the conditions required for steam cracking?

A

-high temperature and steam

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22
Q

what is the structure of alkenes

A

-double covalent bond between two carbon atoms

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23
Q

why are alkenes useful molecules?

Study These Flashcards
A

-they are used to make chemicals called polymers
-they are also used as starting materials for other useful chemicals as well

24
Q

how do we test for alkenes?

Study These Flashcards
A

-we test for alkenes using bromine water which is orange
-we shake our alkene with bromine water and the bromine water turns colourless

25
What are alkenes?
-hydrocarbons with a double carbon-carbon bond.
26
What is the general formula for alkenes?
-𝐶𝑛𝐻2𝑛 ​
27
What are the first four alkenes in the homologous series?
- ethene (C₂H₄) - propene (C₃H₆) - butene (C₄H₈), - pentene (C₅H₁₀).
28
What is the functional group in alkenes?
- the carbon-carbon double bond (C=C).
29
How do alkenes react in combustion reactions?
- Alkenes react with oxygen in combustion reactions, but they tend to burn with smoky flames due to incomplete combustion.
30
why are alkenes called unsaturated molecules ?
-alkenes have two fewer hydrogen atoms than the alkane with the same number of carbon atoms
31
what does 'functional group' mean?
-the part of a molecule that determines how it reacts
32
what kind of series are alkenes?
-homologous series
33
why does combusting an alkene produce unburnt carbon particles?
-incomplete combustion
34
describe the reaction between hydrogen and alkenes?
-this is called hydrogenation -this reaction requires a temperature of around 150 degrees -we need to use a nickel catalyst to speed up the chemical reaction -in this reaction, the two hydrogen atoms add across the double bond. -the carbon to carbon double bond is converted into a carbon to carbon single bond -reacting an alkene with hydrogen produces an alkane
35
what is an alkene?
-unsaturated hydrocarbon that contains a double carbon bond
36
describe the combustion of alkenes?
-they burn with smoky flames due to incomplete combustion.
37
what is an alcohol?
-organic compound that contains an -OH functional group
38
state characteristics of methanol,ethanol,propanol and butanol
-dissolve in water to form a neutral solution -react with sodium to form hydrogen -burn in oxygen -react with carboxylic acids in presence of acid catalyst to form esters
39
oxidation of the alcohols lead to...?
-carboxylic acids
40
what are some uses of alcohols?
-fuels -solvents -drinks
41
how is ethanol produced? + conditions
-Ethanol can be produced by fermentation of sugar with yeast, using renewable sources. ● Conditions: about 35°C, anaerobic (without oxygen) and yeast enzyme catalyst ● Sugar → ethanol + carbon dioxide
42
what are carboxylic acids?
-organic compounds that contain a COOH functional group
43
state the 4 characteristics of carboxylic acids
-dissolve in water to form an acidic solution ( contains H (+) ions ) -react with metal carbonates to form carbon dioxide -react with alcohols with an acid catalyst to produce esters -react with metals to give off hydrogen gas
44
what type of acid is carboxylic acid?
-a weak acid
45
why are carboxylic acids weak acids?
-they are partially dissociated in water, thus the pH of a carboxylic acid in solution is not as low as a solution of strong acid of the same concentration
46
what is an ester and how is it formed? what is characteristic about this class of compounds?
-an organic compound containing a -COO functional group formed from carboxylic acid and alcohol in the presence of a sulfuric acid catalyst -they have a fruity smell
47
What is a polymer? How do molecules containing C=C bond form polymers?
-a polymer is a long chain molecule which is made by lots of smaller molecules joining together -C=C bonds open up and many smaller molecules (monomers) join together to form a polymer chain . -it is called an "addition polymerisation" reaction
48
Give 3 examples of addition polymers and their uses
-Polythene - plastic bags -(poly)tetraflouroethene (PTFE) - teflon surfaces, non stick kitchenware -(Poly)chloroethene (polyvinylchloride, PVC) -water pipes
49
what is a repeating unit of a polymer? + how to draw it
-a smallest structure which, upon numerous translations, yields the structure of the polymer -in addition polymers : to draw it, take a monomer, change C=C to C-C and show additional single bonds extending away from these carbons
50
What is a condensation polymer? How is it made? -There are 2 main groups - name them and give industrially relevant examples.
-a polymer made in condensation polymerisation -in this reaction, many molecules join together, the polymer is formed, but also a small molecule is released -Polyesters e.g terylene -Polyamides e.g Nylon
51
What is an amide bond?
-An amide bond is similar to the ester bond, with O replaced by N -(C=O)-NH(2) -just like an ester , it contains the C=O group
52
what is an amino acid?
-an organic compound that contains both a carboxylic acid functionality ( COOH) and a amine functional group (-NH(2))
53
How do amino acids make proteins ? What are polypeptides?
-By numerous condensation polymerisation reactions ; proteins are polymers made of amino acids (monomers) -polypeptides are also made by condensation polymerisation of amino acids, but are shorter than proteins. One could think about proteins as a product of many polypeptide chains bonded together
54
What are carbohydrates?
-organic molecules made of C,H and O -they are biologically relevant, e.g starch and cellulose -both of these are polymers made of glucose (other carbohydrate) monomers -their structures differ in the way the glucose molecules are joined together
55
What is DNA? Describe its role and structure
-DNA ( deoxyribonucleic acid) is a material that makes up chromosomes - cell structures that store genetic information. -DNA is made of two polymer chains that are held together in a double helix -each polymer chain can be made from 4 different monomers - nucleotides.

Chemistry (11 decks)

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