4.1-4.4. - Organic part 1 Flashcards
(48 cards)
What can organic compounds exist as?
Chains, branched chains or rings of carbon atoms with hydrogen attached.
What are hydrocarbons?
The simplest organic compounds are hydrocarbons. These molecules contains carbon and hydrogen only
What is Empirical formula?
Simples whole number ratio of atoms in a compound that can be calculated
What is the Molecular formula?
Molecular formula counts the actual number of each type of atom present in a molecule.
What is Structual formula?
Shows how the atoms in a molecule are joined together
What is Displayed formula?
Displayed formula shows all the bonds in the molecule as lines each line represents a pair of shared electrons in a covalent bond
How many carbon chains does each code letter has?
Meth - 1
Eth - 2
Prop - 3
But - 4
Pent - 5
Hex - 6
What are Alkanes?
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.
What are Alkenes?
Alkenes are a homologous series of hydrocarbons which contain carbon- carbon double bond why their name ends in ‘ene’.
What are Isomers?
Molecules with the same molecular formula but different structual formula
What is Combustion?
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
What is a Substitution reaction?
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
What is an Addition reaction?
In an addition reaction something is added to a molecule without taking anything away. Alkenes undergo addition reaction like:
CH2CH2 + Br2 > CH2BrCH2Br
What is Crude Oil?
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.
What is the structure of Crude oil?
Crude Oil is a mixture of hydrocarbons compounds containing carbon and hydrogen only many different hydrocarbons of various sizes in crude oil.
How do the properties of Crude Oil change with the size of the molecule?
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
Why is Crude Oil seperated?
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.
What is fractional distillation?
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.
What are some of the uses of crude oil?
What is incomplete combustion?
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.
What are the environmental problems with burning fossil fuels from Crude Oil?
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.
What is the solution to acid rain?
The solution to acid rain involves removing sulfur from fuels scrubbing the gases from power stations and factories to remove the SO2
What is cracking?
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.
What is catalytic cracking?
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.
