Equilibrium And Organic Reactions Flashcards
What is a reversible reaction?
The products react to form the original reactants resulting in opposite energy changes
What is dynamic equilibrium?
If a reversible reaction is carried out in a closed system the forward and backward reactions will eventually happen at the same rate.
The amount of product and reactant are constant
What is Le Chatelier’s principle?
The conditions of the reaction are changed and the closed system will then counteract the change by either favouring the forward or the backward reaction.
Which side does increased concentration of product favour?
Reverse reaction
Which side does increased concentration of reactant favor?
The forward reaction
What does increasing temperature of surroundings do?
Favour endothermic reaction
What does increasing the pressure do?
Favour the reaction that results in fewer molecules
What is crude oil?
Formed from the remains of ancient biomass that died many millions of years ago
Thick black liquid made from a large number of different compounds mixed together, primarily hydrocarbons of various sizes
What are hydrocarbons?
Molecules made from carbon and hydrogen only
What is combustion?
Hydrocarbons are reacted with oxygen to produce lots of energy
What makes a hydrocarbon useful?
Flammability
Boiling point
Viscosity
What are the properties of a long chain hydrocarbon?
Low flammability
High boiling point
High viscosity
What are the properties of a short chain hydrocarbon?
High flammability
Low boiling point
Low viscosity
Do alkanes have single or double bonds?
Single
What is the order of number of carbons?
Meth
Eth
Prop
But
What is the molecular formula of an alkane?
CnH2n+2
What is fractional distillation?
The different hydrocarbons in crude oil are separated into fractions based on their boiling points.
Crude oil is vaporised
Hydrocarbon gases enter and rise up the column
As they rise up the column they cool down and when they reach their boiling point they condense
The hydrocarbon fraction is collected
What is the difference between the top and the bottom of the fractionating column?
Bottom = hotter / long chain hydrocarbons/ 350 degrees
Top = 50 degrees
What are examples of fractions?
Short chain
Gasoline and petrol
Kerosene
Diesel oil and gas
Long chain
What are useful materials produced from fractional distillation?
Solvents, lubricants, polymers, detergents
What is cracking?
Longer molecules less useful than shorter ones
Breaks long chain into small chain
Catalytic cracking = vaporise, hot catalyst
Steam cracking = mix with steam at high temp
What are alkenes ?
Contain double bond between two carbons
More reactive
When mixed with bromine water it turns from orange to colourless
What is the functional group of alkenes?
Two carbons with a double bond
How are alkenes formed?
Cracking
What are alkenes used for?
Formation of polymers
Chemical feedstock
What happens during combustion of alkenes?
Complete = carbon dioxide and water
Incomplete smoky yellow flame = carbon monoxide and soot
Both release less energy than with alkanes
What is addition with halogens in terms of alkenes?
The double bond is broken open and the two halogen atoms add on
What is addition with hydrogen in terms of alkenes?
The double bond is broken open and the two hydrogen atoms add on to form an alkane
What is alkene addition with steam?
React with steam at high pressure and temperature in the presence of a catalyst to form an alcohol
Why are alkenes unsaturated?
They have double bonds
Atoms can be added to the molecule by breaking the double bond
What is the functional group of alcohols?
OH
How are alcohols formed?
Ethanol formed from fermentation of sugar by warming a sealed mixture of yeast and a sugar solution
What are alcohols used in?
Alcoholic drinks
Solvents
Perfumes, aftershaves, mouthwashes
How do alcohols react in combustion?
Combust easily with a blue flame to produce carbon dioxide and water
How do alcohols react with sodium?
Release hydrogen and a alkoxide which if added to water forms a strong alkaline solution
What is oxidation of alcohols?
Reacts with oxidising agents, such as dichromate to form carboxylic acids
What is the functional group of carboxylic acids?
COOH
How are carboxylic acids formed?
Oxidation of alcohols
What are uses of carboxylic acids?
Ethanoic acid is used in vinegar
Do carboxylic acids generally undergo combustion?
No
How do carboxylic acids react with sodium carbonate?
Salt, carbon dioxide and water
How do carboxylic acids react with alcohols?
Produce esters
What are esters used for?
Perfumes
Flavourings
Are carboxylic acids strong or weak acids?
Weak
What is the monomer for enzymes and proteins?
Amino acids
