Organic Flashcards
Organic Chemistry
Study of the compounds of carbon
Hydrocarbon
A compound that only contains carbon and hydrogen
Fossil fuels
Fuels that were formed from the remains of plants and animals that lived millions of years ago
Saturated compound
There are only single bonds between the atoms in the molecule (Alkanes)
Homologous series
A series of compounds of similar chemical properties, showing gradations (successive changes) in physical properties , and having a general formula for its members. Each member has a similar method of preparation, and each memeber differs from the previous member by a CH2 unit
Structural isomers
Compound with the SAME MOLECULAR formula but different structural formulas (e.g 3 isomers of pentane)
Unsaturated compound
A compound that contains 1+ or more double/triple bonds between the atoms in the molecule (e.g. Alkenes)
Aliphatic compound
An organic compound that consists of open chains of carbon atoms and closed chain compounds(rings) that resemble them in chemical properties
Aromatic compounds
Compounds that contain a benzene ring structure in their molecules
What about benzene (discovered by Michael Faraday) puzzled chemists?
- Reactivity (predicted- highly reactive, actually not)
2. Bond lengths (all the c-c bond lengths are the same, single usually longer)
Auto-ignition
Early ignition of the petrol-air mixture before normal ignition of the mixture by a spark
Octane number
The measure of the tendency of the fuel to resist knocking
e.g. 2,2,4-trimethylpentane used because it has a low tendency, and an octane no. of 100
Catalytic cracking
The breaking down of long—chain hydrocarbon molecules into short-chain molecules by the action of heat & catalysts
(Greater demand for shorter, higher octane no. & more branched)
Benefit of catalytic cracking?
Alkenes produced are used to manufacture various materials, e.g. ethene—>polyethene—>making plastic bags
Important for the petrochemicals industry
Heat of reaction
The heat change when the numbers of moles of reactants indicated in the balanced eqn. for the reaction react completely
Heat of combustion
The heat change when one mole of a substance is completely burned in excess Oxygen.
Measured using a bomb calorimeter
Calorimeter
Any container used for the determination of heat changes (e.g. bomb calorimeter- measuring heat if combustion)
Kilogram calorific value
The heat energy produced when 1kg of the fuel is completely burned in oxygen
Use- helps us to compare the efficiency of various fuels
Name a fuel with a high kilogram calorific value
Methane- an excellent fuel
What happens when a chemical reaction occurs?
Bonds are broken & new bonds are formed
-Energy required to break bonds & energy released when they’re formed
Bond energy
The average energy required to break one mole of a particular covalent bond and to separate the neutral atoms completely from each other
Why are bond energy values an average of energy?
Bond energy for a particular bond can vary
Neutralisation
The reaction between an acid and a base to form salt and water
-e.g. Acid(HCL)+base(NaOH)=NaCl+ H2O
Heat of neutralisation
The heat change when one mole of H+ ions from an acid reacts with one mole of OH- ions from a base
-measured in kJmol-1
Heat of formation
The heat change that takes place when one mole of a compound in its standard state is formed from its elements in their standard state
Hess’s Law
If a chemical reaction takes place in a number of stages, the SUM of the HEAT CHANGES in the separate stages is equal to the heat change if the reaction is carried out in one stage
(Amount of heat absorbed in a chemical reaction is the same no matter how many steps it takes place in)
Why is Hess’s Law so useful?
Allows thermochemical eqns. to be added, subtracted, multiplied, or divided to find the unknown heats of reaction.
(Useful in thermochemistry)
The Law of Conservation of Energy
Energy can’t be created or destroyed, it can only be converted from one form of energy to another
One form of energy—> another
Functional group
An atom/group of atoms that’s responsible for the characteristic properties of an organic compound/series of organic compounds
Primary alcohol
Where the Carbon atom joined to the -OH group is attached to only one other Carbon atom
Secondary alcohol
When the Carbon atom joined to the -OH group is joined to 2 other Carbon atoms
(E.g. Ethanol)