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EQUILIBRIA, ENERGETICS AND ELEMENTS

RATE OF REACTION

There are many different ways of following the rate:

Gas volume ­ if a gas is given off, you could collect in a gas syringe and record how much you
get at regular time intervals.

Colour change ­ you can track the colour…

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The
rate
is




The rate is proportional to the
Changing the concentration proportional to the concentration
[concentration]² ORDER 2
doesn't change the rate ORDER ORDER 1
0 Half-life increases
Half-life stays the same ­
Half-life decreases independent of the concentration.




The effect of a temperature change on k

When the…

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Dynamic Equilibrium ­ rate of the forward and reverse reactions are equal and concentrations of
reactants and products are constant.

Kc is an equilibrium constant, measured using concentrations ­ NOT SOLIDS!! The only factor that
affects Kc is temperature, NOT pressure, concentration or catalysts!

Exothermic reaction Endothermic reaction

Temperature raised…

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Weak acids

Weak acids are poor proton donors and are only partially dissociated in aqueous solution.
Therefore the dissociation isn't 100% and [H+] can't be calculated directly from
concentration of acid.
Ka shows the extent of acid dissociation.
Equilibrium constant for this reaction is HA(aq) H+(aq) + A-(aq)




Kw =…

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A buffer solution is one that minimises pH changes on addition of small amounts of acid and base.
Buffers are important solutions especially in biological systems.

A buffer solution can be made from a weak acid and a salt of the weak acid (CHCOOH/CHCOONa)

Role of the acid-base pair:

The…

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D-block elements that have an ion with an incomplete d sub shell are transition elements. Transition
elements are special because they:

Variable oxidation states

Form coloured ions

Good catalysts

Form complex ions

[Cu(HO)]² ­ Blue sol [Cu(HO)(OH)] ­ Blue [CuCl]² ­ yellow sol [Cu(NH)(HO)]² ­
ppt (appears green) Deep blue…

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A ligand must have at least 1 lone pair of electrons; otherwise it won't be able to form a coordinate
bond. Ligands with 1 pair ­ monodentate. Ligands with 2 lone pairs - bidentate (en). Ligands with
more than 2 lone pairs ­ multidentate.

All Complex ions can have Stereoisomers,…

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more negative the LE (more exothermic), the stronger the bonding.

Ionic charge ­ higher the charge on the ions, more energy is released when an ion lattice forms and
the LE will be more negative (more exothermic).

Ionic size ­ smaller the ionic radii of the ions, more negative (more…

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If G is ­ve then it is a feasible reaction. If it's a +ve value, it's not feasible. * Even if it is ­ve, the
reaction might have high activation energy and therefore not work.

Some endothermic reactions can happen spontaneously, if the entropy is high enough the reaction
will…

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Reaction might be so slow that you can't even see it happening

Storage and fuel cells

Modern energy storage cells work just like electrochemical cells. A fuel cell uses the energy from a
reaction of a fuel with an oxidant ­ usually oxygen ­ to create a voltage.

Hydrogen-oxygen fuel…

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