OCR A Chemistry F325 Definitions

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Rate of reaction
The change in concentration of a reactant or product per unit time.
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Order of a reactant
The power of the concentration of a particular reactant to which the rate of reaction is directly proportional.
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Rate constant
A coefficient of proportionality relating the rate of a chemical reaction at a given temperature to the product of the concentrations of reactants.
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Half-life
The time it takes for the concentration of a particular reactant to reduce by half.
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Rate-determining step
The slowest step in a reaction mechanism that limits the rate of the overall reaction.
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pH
pH=-log[H+]
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[H+]
[H+]=10^(-pH)
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Ionic product of water, Kw
Kw=[H+][OH-]
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Buffer solution
A system that minimises pH changes on addition of small amounts of an acid or a base.
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Enthalpy change of neutralisation
The energy change that occurs when solutions of an acid and an alkali react together under standard conditions to produce one mole of water.
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Lattice enthalpy
The enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions.
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Enthalpy change of solution
The enthalpy change of solution is the enthalpy change when one mole of an ionic substance dissolves in water.
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Enthalpy change of hydration
The enthalpy change when one mole of gaseous ions dissolve in water.
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Free energy change
ΔG = ΔH - TΔS where ΔG = free energy change, ΔH = enthalpy change, T = absolute temperature, and ΔS = entropy change.
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Redox
A process in which one species is reduced and other oxidised.
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Oxidation number
A number assigned to an element that represents the number of electrons lost, or gained, by an atom of that element.
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Half-reaction
The oxidation or reduction component of a redox reaction.
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Oxidising agent
A species that brings about oxidation by being reduced.
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Reducing agent
A species that brings about reduction by being oxidised.
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Standard electrode potential
The e.m.f. of a half cell compared with the standard hydrogen half-cell at 298K, a pressure of 100kPa and with a solution concentration of 1 mol/dm^3.
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Transition element
A d-block element that can form an ion with an incomplete d sub-shell.
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Ligand
An ion or molecule attached to a metal ion by coordinate bonding.
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Complex ion
An ion surrounded by ligands.
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Coordination number
The number of ligands bonded to the central ion in a complex ion.
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Bidentate ligand
A ligand that forms two coordinate bonds.
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Other cards in this set

Card 2

Front

The power of the concentration of a particular reactant to which the rate of reaction is directly proportional.

Back

Order of a reactant

Card 3

Front

A coefficient of proportionality relating the rate of a chemical reaction at a given temperature to the product of the concentrations of reactants.

Back

Preview of the back of card 3

Card 4

Front

The time it takes for the concentration of a particular reactant to reduce by half.

Back

Preview of the back of card 4

Card 5

Front

The slowest step in a reaction mechanism that limits the rate of the overall reaction.

Back

Preview of the back of card 5
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