LATTICE ENTHALPY

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Define lattice enthalpy
when one mole of an ionic lattice is formed from its gaseous ions under standard conditions
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What is lattice enthalpy?
measure of ionic bond strength/ cannot be measured directly/ always exotermic
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What two factors impact upon lattice enthalpy?
atomic radius and atomic charge
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How does atomic radii impact upon lattice enthalpy?
larger the ions, less negative the enthalpies of formation (weaker lattice) as ions ar larger the charges become further apart and so have weaker attractive forces
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How does atomic charge impact upon lattice enthalpy?
big the change go the ion, greater the attraction between the ions so stronger lattice (more exothermic)
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What is the standard enthalpy change of formation?
enthalpy change when one mole of substance is formed form its elements, under standard conditions
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What is the standard enthalpy change of atomisation?
enthalpy change required to form one mole of gaseous atoms from the element in their standard state
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What is the first ionisation energy?
enthalpy change when one mole of gaseous +1 ions are formed from their gaseous element under standard conditions
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What is first electron affinity?
enthalpy change when one mole of gaseous -1 ions are removed from gaseous atoms under standard conditions
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second ionisation energy
energy required to remove one mole of electrons from one mole of gaseous +1 ions under standard conditions
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what is second electron affinity?
enthalpy change when one mole of e are added to one mole of gaseous -1 ions under standard conditions
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Why is second electron affinity always positive?
energy needed to add electrons, like charges repel
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Define enthalpy change of solution
enthalpy change when one mole of an IONIC compound is completely dissolved in water
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Define enthalpy change of hydration
enthalpy change when one mole of gaseous ions fully dissolve in water
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Why is enthalpy change of hydration always exothermic?
dissociation due to polar H2O molecule - bonds formed so energy released
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How do you calculate enthalpy change of solutions? How do you know if it is exothermic or endothermic?
total HYD - LE// if LE is bigger than total HYD is endothermic/ if total HYD is bigger than LE its exothermic
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Card 2

Front

What is lattice enthalpy?

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measure of ionic bond strength/ cannot be measured directly/ always exotermic

Card 3

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What two factors impact upon lattice enthalpy?

Back

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Card 4

Front

How does atomic radii impact upon lattice enthalpy?

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Card 5

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How does atomic charge impact upon lattice enthalpy?

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