Definitions for aqa unit 2 chemistry

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  • Created by: Clare
  • Created on: 09-05-14 09:16
Enthalpy Change
Change in heat energy under constant pressure.
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Standard Conditions
100kPa and a stated temperature, usually 298K/25 C
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Exothermic
A change during which heat is given out by particle.
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Endothermic
A change in which heat is absorbed by particles.
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Standard Enthalpy of Formation
Heat energy change when one mole of a compound is formed from its elements in their standard states under standard conditions.
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Standard Enthalpy of Combustion
Heat energy change when one mole of a substance is completely burned in excess oxygen under standard conditions.
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Activation Energy
The minimum energy required for a collision to be successful.
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Collision Frequency
The number of collisions between particles per second.
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Collision Energy
The combined kenetic energy of colliding particles.
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Rate of Reaction
The change in concentration of a species per unit of time.
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Catalyst
A substance which increases the rate of a chemical reaction without itself being chemically change at the end of the reaction.
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Dynamic Equilibrium
A reaction in which the forward and reverse reactions are proceeding at the same rate, so the concentrations of reactants and products are constant
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Le Chatelier's Principle
If a change in conditions is imposes on a system at equilibrium, the system will react in such a way as to oppose the effect of the change.
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Oxidation
Loss of elections OR the addition of oxygen OR the removal of hydrogen
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Reduction
Gain of electrons
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Oxidising agent
Electron acceptor
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Reducing Agent
Electron Donor
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Oxidation Number
The charge that would be on an atom if the bonding were completely ionic.
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Redox Reaction
A reaction in which electrons a transferred from one species to another.
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Geometric Isomerism
The same molecular formula, but a different spatial arrangement of atoms around a double bond.
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Addition
Combination of two or more molecules to form a single molecule.
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Substitution
Replacement of one atom or group of atoms by another
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Elimination
Loss of a small molecule from a larger one to form an unsaturated compound.
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Electrophile
Species which can accept an electron pair from another species.
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Nucleophile
Species which can use a lone pair of electrons to form a covalent bond.
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Free Radical
Species with an unpaired electrons
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Homolytic Fission
Breaking of a covalent bond in such a way that one electron goes to each atom
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Heterolytic Fission
Breaking of a covalent in such a way that both electrons go to the same atom
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Hydration
Addition of water to a species
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Hydrolysis
Use of water to break covalent bonds
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Addition Polymerisation
Combination of a large number of monomers to form a single chain
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Biofuel
A fuel derived of produced from renewable biological sources
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Other cards in this set

Card 2

Front

100kPa and a stated temperature, usually 298K/25 C

Back

Standard Conditions

Card 3

Front

A change during which heat is given out by particle.

Back

Preview of the back of card 3

Card 4

Front

A change in which heat is absorbed by particles.

Back

Preview of the back of card 4

Card 5

Front

Heat energy change when one mole of a compound is formed from its elements in their standard states under standard conditions.

Back

Preview of the back of card 5
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