calculating enthalpy change

enthalpy change question (formation)

C6H6 + 7.5 O2 → 6 CO2 + 3 H2O

🔺H Overall : - 3267

🔺H CO2: - 394

🔺H O2: - 268

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what is involved in forming an ionic bond

metal starts as giant lattice

non metal consist of molecules

metal starts as giant lattice

requires energy to separate ( enthalpy change of atomisation) and remove electrons (ionisation )

non metal consist of molecules

requires energy to separate ( enthalpy change of atomisation) and energy involved in adding electron to non metal ( electron affinity)

why is ionic crystal stable ?

Because of the large release of energy when oppositely charge ions come together 

is lattice enthalpy exo or endo ?

Exothermic because energy is given out when an ionic bond formed from gaseous ions.

what does the lattice enthalpy shows

show strength of a ionic lattice, large negative values shows a strong bond strength. 

can lattice enthalpy be measured ?

no it cannot because it’s impossible to form one mole of an ionic lattice from gases ion. 

how to calculate the lattice enthalpy of formation  ? 

lattice enthalpy of formation  = - (electron affinity) - (ionisation) - ( atomisation) - ( atomisation) + (enthalpy of formation) 

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