CH2 Definitions

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  • Created by: zopetre_
  • Created on: 27-05-17 20:44
Exothermic reaction
One that releases energy to surroundings, temperature rise and ΔH is negative
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Endothermic reaction
One that takes in energy from the surroundings, temperature drop and ΔH is positive
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Enthalpy, H
The heat content of a system at constant pressure
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Enthalpy change, ΔH
The head added to a system at constant pressure
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Principle of conservation of energy
States that energy cannot be created or destroyed, only changed from one form to another
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Hess's Law
States that the total enthalpy change for a reaction is independent of the route taken from the reactants to the products
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Bond enthalpy
The enthalpy required to break a covalent X-Y bonds into X atoms and Y atoms, all in the gas phase
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Average bond enthalpy
The average value of the enthalpy required to break a given type of covalent bond in the molecules of a gaseous species
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The rate of reaction
The change in concentration of a reactant or product per unit time
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Activation energy
The minimum energy required to start a reaction by breaking bonds
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Catalyst
A substance that increases the rate of a chemical reaction without being used up in the process, provides alternative pathway by lowering activation energy
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Homogeneous catalyst
In the same phase as the reactants
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Heterogeneous catalyst
In a different phase from the reactants
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Functional group
Refers to the atom/group of atoms that gives the compound its characteristic properties
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Homologous series
A series of compounds with the same functional group
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Saturated compound
One that contains no C to C multiple bonds
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Hydrocarbon
A compound of carbon and hydrogen only
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Unsaturated compound
One that contains C to C multiple bonds
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Molecular formula
Shows the atoms and how many of each type there are, in a molecule of a compound
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Displayed formula
Shows all the bonds and atoms in the molecule
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Shortened formula
Shows the groups in sufficient detail that the strucutre is unambiguous
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Skeletal formuls
Shows the carbon/hydrogen backbone of the molecule as a series of bonds with any functional groups attached
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Structural isomers
Compounds with the same molecular formula with different structural formula
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E-Z isomerism
Isomerism that occurs in alkenes due to restricted rotation about the double bond
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Fossil fuel
One that is derived from organisms that lived long ago
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Non-renewable resources
Those that cannot be reformed in a reasonable timescale
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Greenhouse gas
One that causes an increase in the Earth's temperature
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Acid rain
Rain with lower than expected pH
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Complete combustion
Combusion that occurs with excess oxygen
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Incomplete combustion
Combustion that occurs with insufficient oxygen
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Halogenation
A reaction with any halogen
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Initiation
The reaction that starts the process
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Homolytic bond fission
When a bond is broken and each of the bonded atoms receives one of the bonded electrons
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Radical
A species with an unpaired electron
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Propagation
The reaction by which the process continues/grows
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A chain reaction
One that involves a series of steps and once started, continues
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Termination
The reaction that ends the process
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A reaction mechanism
Shows the stages by which a reaction proceeds
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A substitution reaction
One in which one atom/group is replaced by another atom/group
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A π bond
One formed by the sideways overlap of p electrons
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Electrophile
An electron-deficient species that can accept a lone pair of electrons
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Heterolytic bond fission
When a bond is broken and one of the bonded atoms receives both of the bonded electrons
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Addition reaction
A reaction in which reagents combine to give one product
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Carbocation
A carbon containing positively charged ion
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Polymerisation
The joining of a very large number of monomer molecules to make a large polymer molecule
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Monomer
A small molecule that can be made into a polymer
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Repeat unit
The section of the polymer that is repeated to make the whole structure
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Halogenoalkane
An alkane in which one or more hydrogen atoms have been replaced by a halogen
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Nucleophile
A species with a lone pair of electrons that can be donated to an electron deficient species
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Reflux
Process of continuous evaporation and condensation
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Hydrolysis
A reaction with water to produce a new product
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CFCs
Halogenoalkanes containing both chlorine and fluorine
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Ozone layer
A layer surrounding the earth that contains O3 molecules
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HFCs
Halogenalkanes containing fluorine as the only halogen
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Alcohol
An homologous series containg -OH as the functional group
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Fermentation
An enzyme-catalysed reaction that converts sugars to ethanol
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Biofuel
A fuel that has been produced using a biological source
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Classification of alcohols
Primary, secondary or tertiary according to structure
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Carboxylic acid
Homologous series containing -COOH as the functional group
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Molecular ion
The positive ion formed in a mass spectrometer from the whole molecular
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Fragmentation
Splitting of molecules in a mass spectrometer into smaller parts
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Wavenumber
A measure of energy absorbed used in IR spectra
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Chemical shift
A measure of different in parts/million from the standard of the energy of a particular absorption type
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Other cards in this set

Card 2

Front

Endothermic reaction

Back

One that takes in energy from the surroundings, temperature drop and ΔH is positive

Card 3

Front

Enthalpy, H

Back

Preview of the front of card 3

Card 4

Front

Enthalpy change, ΔH

Back

Preview of the front of card 4

Card 5

Front

Principle of conservation of energy

Back

Preview of the front of card 5
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