C7: Organic chemistry Flashcards
what is crude oil? is it finite?
- a mixture of compounds
- a fossil fuel consisting of the remains of ancient biomass
- finite resource - cannot be replaced as it is used up
What is a hydrocarbon?
- a compound made up exclusively of hydrogen and carbon atoms
What are alkanes and their formula?
Saturated hydrocarbons of a general formula
CₙH₂ₙ₊₂
what is a homologous series ?
- Series of compounds with the same:
- general formula,
- functional groups
- and similar chemical properties
Describe the combustion of hydrocarbons
- exothermic reaction occurs when hydrocarbons are reacted with oxygen
- complete combustion produces carbon dioxide and water ( carbon and hydrogen atoms are completely oxidised
- incomplete combustion produces carbon or carbon monoxide and water
Describe the 3 physical properties of alkanes
- boiling points and viscosity increase as molecules get bigger
- volatility and flammability decrease as molecules get bigger
- poor reactivity
define ‘cracking’?
when large hydrocarbons are thermally broken down into smaller and useful molecules
What type of reaction is cracking?
Thermal decomposition
what are the two types of cracking ?
- catalytic cracking: reactant heated to vapour passed over a hot catalyst
- steam cracking: heated to vapour , mixed with steam and heated to high temperatures
How are the products of cracking used?
The products are alkanes and alkenes
- used as polymers and starting materials for synthesis
Explain how fractional distillation of crude oil takes place
- Crude oil is heated and vapourised
- vapour rises up the fractionating column
- the column is hotter at the bottom and cooler at the top
- Hydrocarbons cool as they go up the column and condense at different heights, as they have different boiling points
- large molecules , high boiling points - at bottom
- small molecules , low boiling points - at the top
What is an alkene
- unsaturated hydrocarbon
- contains a C=C bond
- general formula for alkenes is CₙH₂ₙ
What is the test for alkenes?
- Add bromine water
- Colour change occurs from orange to colourless
Describe the combustion of alkenes
- they burn with smoky flames due to incomplete combustion
What are the reaction conditions for
addition polymerisation?
●High temperature
● High pressure
● Titanium catalyst
State the differences
between addition and condensation polymerisation
- In addition polymerisation, only one product is formed whereas in condensation polymerisation two different products are formed (the polymer and a small molecule)
- Condensation polymerisation involves
monomers with 2 different functional group
whereas addition polymerisation involves just 1
functional group
Describe the three addition reactions of alkenes and their requirements
- with hydrogen: hydrogenation ; requires a higher temperature and a nickel catalyst
- with steam - hydration ; requires high temperature, pressure and concentrated phosphoric acid as a catalyst
- With Br₂/Cl₂/I₂ - addition of halogens
What is an alcohol?
- an organic compound that contains an -OH functional group
State the names and chemical formulae of
the first 4 members of the homologous series
of alcohols
● Methanol (CH₃OH)
● Ethanol (C₂H₅OH)
● Propanol (C₃H₇OH)
● Butanol (C₄H₉OH
State the structural formula for the first 4
members of the homologous series of
alcohols
● Methanol – CH₃OH
● Ethanol – CH₃CH₂OH
● Propanol – CH₃CH₂CH₂OH
● Butanol – CH₃CH₂CH₂CH₂OH
State characteristics of the first 4 alcohols
- dissolve in water to form a neutral solution
- react with sodium to form hydrogen and sodium ( ethoxide eg)
- burn in oxygen
- react with carboxylic acids in presence of acid catalyst to form esters
What happens when
an alcohol reacts with an
oxidising reagent?
A carboxylic acid is produced
State 3 uses of alcohols
● Solvents
● Alcoholic drinks
● Fuels
State the conditions required for fermentation of glucose and state the equation of the reaction
- 30℃
- aqueous solution of the glucose
- absence of air
- yeast added
C₆H₁₂O₆ → 2C₂H5OH + 2CO₂
How is ethanol made
from glucose?
Ferment sugar solutions (glucose) using yeast
What is observed
when ethanol burns in
air?
A clean blue flame
What is the word
equation for the
complete combustion of
ethanol?
Ethanol + oxygen → carbon dioxide + water
What is observed
when alcohols react with
sodium metal?
The sodium effervesces (gives off bubbles of gas
What is the word
equation for the reaction
of sodium with ethanol?
Sodium + Ethanol Sodium ethoxide + Hydrogen
What happens when
alcohols are added to
water?
They mix and a neutral solution is produced
What is the word equation for the reaction
of sodium with ethanol?
Sodium + Ethanol Sodium ethoxide + Hydrogen
What is the balanced
chemical equation for
the complete
combustion of ethanol?
C₂H₅OH + 3O₂ 2CO₂ + 3H₂O
What are carboxylic acids?
organic compounds that contain a COOH functional group
State 4 characteristics of carboxylic acids
- dissolve in water to form an acidic solution ( contains H+ ions)
- react with metal carbonates to form carbon dioxide , the salt and water
- react with alcohols with a sulfuric acid catalyst to produce esters
- react with metals to give off hydrogen gas
State 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
What type of acid is a carboxylic acid?
- it is a weak acid
Explain why carboxylic acids are weak acids?
- they are partially dissolved in water , thus the pH of a carboxylic acid in solution is not as low as a solution of a strong acid of the same concentration
State the names and
chemical formulae of
the first 4 members of
the homologous series
of carboxylic acids
● Methanoic acid (HCOOH)
● Ethanoic acid (CH₃COOH)
● Propanoic acid (C₂H₅COOH)
● Butanoic acid (C₃H₇COOH
What is the structural
formula for the first four
members of the
homologous series of
carboxylic acids?
● Methanoic acid - HCOOH
● Ethanoic acid - CH₃COOH
● Propanoic acid - CH₃CH₂COOH
● Butanoic acid – CH₃CH₂CH₂COOH
What happens when
carboxylic acids dissolve
in water?
An acidic solution forms
What is formed
when a carboxylic acid
reacts with a metal
carbonate?
A salt, carbon dioxide and water
State the word
equation for the reaction
between ethanoic acid
and sodium carbonate
Ethanoic acid + Sodium carbonate ➝ sodium
ethanoate + water + carbon dioxide
What is an ester and how is it formed?
- an organic compound containing a -COO- functional group , formed from carboxylic acids and alcohol in the presence of a sulfuric acid catalyst
- they have a fruity smell
State the word
equation for the reaction
of ethanoic acid with ethanol in the presence
of sulphuric acid catalyst
Ethanoic acid + Ethanol ⇋ Ethyl ethanoate + wate
State 2 properties of
esters
● Pleasant smell
● Volatile (low boiling point)
State 2 uses of esters
● Perfumes
● Food flavourings
what is a polymer
- a polymer is a long chain molecule which is made up of lots of smaller molecules joining together ( monomers
How do molecules containing C=C bond form polymers?
C=C bonds open up and many smaller molecules ( monomers) join together to form a chain
Give three examples of addition polymers and their uses.
Polyethene : plastic bags
(Poly)tetrafluoroethene (PTFE) : teflon surfaces, for use in non stick kitchenware
(Poly) chloroethene (polyvinylchloride, PVC) - water pipes
What is a repeating unit of a polymer?
It is a smaller structure which, upon numerous translations, yields the structure of the polymer
How many different
functional groups does
an amino acid molecule
have?
two
What are the two
different functional
groups in a molecule of
amino acid?
● -COOH
● -NH2
- What type of
reaction occurs for
amino acids to produce
a polypeptide?
Condensation polymerisation reaction
What is an amino acid?
- it is an organic compound that contains both a carboxylic acid functionality ( COOH) and an amine functional group (-NH2)
How do amino acids make proteins?
through numerous condensation polymerisation reactions; proteins are polymers made of amino acids ( monomers)
what are polypeptides?
- made up of condensation polymerisation of amino acids , but are shorter than proteins.
What are carbohydrates?
- they are organic molecules made of C, H and O.
- Polymers made of glucose monomers
- their structures differ in the way the glucose molecules are joined together.
What is DNA?
DNA is a material that makes up chromosomes - cell structures that store genetic information
describe the role and structure of DNA
DNA is made up of two polymer chains that are held together in a double helix
- each polymer chain can be made from 4 different monomers
- nucleotides
What does a
nucleotide monomer
consist of?
A phosphate group attached to a sugar molecule
attached to one of four bases
