Equilibria, Energetics and Elements Definitions

All (or so i hope) of the definitions you should know for Chemistry OCR F325.

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RATE OF REACTION:-

The change in concentration of a reactant or product per unit of time.

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INITIAL RATE OF REACTION:-

The change in concentration of a reactant or product per unit of time at the start of the reaction when t=0.

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RATE CONSTANT (k):-

The constant that links the rate of the reaction to the concentrations of reactants raised to the powers of their orders.

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OVERALL ORDER:-

The sum of individual orders ---> rate = k [A] [B]  so Overall order ---> 1+1 =2.

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HALF-LIFE:-

The time taken for the concentration of the reactant to reduce by half.

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EQUIVALENCE POINT:-

The point in a titration when the volume of one solution has reacted exactly with the volume of the second solution.

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END POINT:-

When there are equal concentrations of the weak acid and the conjugate base forms of the indicator.

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STEREOISOMER:-

Species with the same structural formula but a different arrangement of atoms in space.

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OXIDATION:-

Loss of electrons ( Oxidation Is Loss ).

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REDUCTION:-

Gain of electrons ( Reduction Is Gain ).

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STANDARD ENTHALPY CHANGE OF NEUTRALISATION:-

The enthalpy change that accompanies the neutralisation of an acid (aq) by a base (aq) forming 1 mole of water under standard conditions.

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LIGAND SUBSTITUTION:-

A reaction when one ligand in a complex ion is replaced by another ligand.

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ENTROPY:-

The quantative measure of the degree of disorder in a system.

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STANDARD ENTROPY CHANGE OF REACTION:-

The entropy change that accompanies a reaction in the molar quantities expressed in a chemical system under standard conditions, all reactants and products in their standard states.

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FREE ENERGY CHANGE:-

The balance between enthalpy, entropy and temperature ---> ΔG = ΔH -TΔS. (Convert all into same units as ΔH kJ/mol and ΔS J/mol.)

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STANDARD ELECTRODE POTENTIAL:-

The electromotive force of a half cell compared with a standard hydrogen half cell at 298K, 100kPa, 1mol/dm³.

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COMPLEX ION:-

A transition metal bonded to one or more ligands by coordinate bonds (dative covalent bonds).

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LIGAND:-

A molecule/ion that can donate a pair of electrons with the transition metal forming a coordinate bond.

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COORDINATION NUMBER:-

The total number of coordinate bonds formed between the transition metal ion and its ligands.

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TRANSITION ELEMENT:-

A d-block element that forms an ion with an incomplete 'd' sub-shell.

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STABILITY CONSTANT (Kstab):-

The equilibrium constant between a transition metal ion surrounded by water ligands and the complex ion formed when the same ion has undergone ligand substitution.

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DYNAMIC EQUILIBRIUM:-

When k=0 and the forward reaction equals the backward reaction in a closed system.

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Kc > 1:-

The reaction is product favoured.

Δ     ---->    Δ

Reactants      Products

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Kc < 1:-

The reaction is reactant favoured.

Δ    ---->    Δ  

Reactants                      Products

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BRONSTED-LOWRY ACID:-

A proton donor. A proton can be removed from it.

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