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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Saravanan on September 12, 2014, 07:04:04 AM

Title: Determining Lattice enthalpy only by Born Haber cycle ?
Post by: Saravanan on September 12, 2014, 07:04:04 AM

Why is it impossible to determine lattice enthalpy directly by experiment when we are able to determine enthapy of formation experimentally ?

Title: Re: Determining Lattice enthalpy only by Born Haber cycle ?
Post by: mjc123 on September 12, 2014, 11:50:27 AM

Because you can't take an ionic solid and convert it into a gas of ions. That's not a physically realistic process. You have to infer it using a Born-Haber cycle and other quantities that can be determined experimentally.

Title: Re: Determining Lattice enthalpy only by Born Haber cycle ?
Post by: Saravanan on September 13, 2014, 03:47:08 AM

Thanks for your answer

Title: Re: Determining Lattice enthalpy only by Born Haber cycle ?
Post by: AdiDex on September 13, 2014, 01:08:57 PM

The answer is hidden in the Definition Of "Lattice Enthalpy"...

Which states that the total enthalpy change if the component ions (Gaseous) were brought together from infinity.

As you can't seperate them to the infinite ..
You also know that you can't find the total enthalpy of system , you can just find enthalpy change .
The reason is similar .
Because you can't destroy it completely so you can check total enthalpy consisting in it...