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1.Enthalpy changes and ionic bonding
When metals react with non-metals, the ions produced form ionic crystals. These ionic
crystals are giant lattices consisting of positive and negative ions packed in a regular

Standard enthalpy changes
The standard conditions are:
Temperature of 25C (298K)
Pressure of 1 atmosphere…

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The first ionisation energy of an element is the energy needed to remove one
electron from each atom in one mole of gaseous atoms of the element to form one mole
of gaseous +1 ions under standard conditions
Na(g) --> Na+(g) + e- HI.1[Na(g)]=+496kJmol-1
Successive ionisation energies for…

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A Born-Haber cycle identifies all the enthalpy changes that contribute to the standard
enthalpy change of formation of a compound. These changes involve:
The enthalpy changes required to create free gaseous ions by atomising and
then ionizing the elements
The energy given out (the lattice enthalpy) when the…

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4.Enthalpy changes during dissolving
An ionic compound such as sodium chloride does not dissolve in non-polar solvents
like hexane, but it will dissolve in a polar solvent like water. When one mole of
sodium chloride dissolves in water to produce a solution of concentration 1 moldm-3
under standard…

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Furthermore, both processes become more exothermic as the charges on the ions
increase because the charge density of an ion increases and therefore its attraction for
any opposite charge increases.

The effect of ionic radius on enthalpy change of hydration and lattice enthalpy
As the radius of an…


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