Term
| Lattice enthalpy of formation |
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Definition
| Enthalpy change for 1 mol of a molecule from its ions in the gaseous state |
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Term
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Definition
| Enthalpy change when 1 mol of gaseous ions is converted into aqueous ions (or converted to an aqueous solution) |
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Term
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Definition
| Only ionic bonds between atoms and ions are perfect spheres |
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Term
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Definition
| Enthalpy change for the formation of 1 mol of gaseous atoms from the element in their standard states |
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Term
| Enthalpy of lattice dissociation |
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Definition
| Enthalpy change to separate 1 mol of an ionic lattice into its gaseous ions |
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Term
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Definition
| Enthalpy change when 1 mol of gaseous atoms become negatively charged ions |
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Term
| Bond dissociation enthalpy as applied to chlorine |
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Definition
| Enthalpy change to break the bond in 1 mole of chlorine molecules to form 2 moles of gaseous chlorine atoms |
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Term
Why is the enthalpy of atomisation of chlorine is exactly half the bond
dissociation enthalpy of chlorine? |
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Definition
For atomisation, only 1 mole of chlorine atoms, not 2 moles as in
bond enthalpy. |
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Term
Why is the lattice dissociation enthalpy of magnesium chloride is greater than that
of calcium chloride? |
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Definition
| The magnesium ion is smaller so attraction to the chloride ion stronger |
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Term
Why is the lattice dissociation enthalpy of magnesium oxide is greater than that of
magnesium chloride? |
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Definition
| The oxide ion has a greater charge so attracts the magnesium ion more strongly |
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Term
how can the quantities of enthalpy change (ΔH), entropy change (ΔS) and
temperature (T) be used to predict whether a change is feasible. |
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Definition
∆G = ∆H – T∆S
If ∆G is less than or equal to 0 reaction is feasible |
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Term
Explain why the evaporation of water is spontaneous even though this change is
endothermic.
In your answer, refer to the change in the arrangement of water molecules and the
entropy change. |
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Definition
The molecules become more disordered when water changes from a liquid to a gas therefore the entropy change is positive
T∆S>∆H
∆G<0 |
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