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Postby Jesse_torres2H » Sun Feb 11, 2018 9:33 pm

I was working on the practice midterm and on question 2C it mentions the enthalpy of sublimation of graphite. What exactly is enthalpy of sublimation and when do we use it?

Curtis Wong 2D
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Re: Sublimation

Postby Curtis Wong 2D » Sun Feb 11, 2018 9:37 pm

Sublimation is the change of a solid to a gas. So in order to find the enthalpy for it, simply do the enthalpy of fusion + enthalpy of vaporization.

Julian Krzysiak 2K
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Re: Sublimation

Postby Julian Krzysiak 2K » Sun Feb 11, 2018 9:42 pm

The only places where I've seen Enthalpy of Sublimation for a specific substance used is when we are using mean bond enthalpies to calculate the enthalpy for the reaction.

We would use sublimation when we need to create a new molecule in a gaseous form, but one of the reactants is in a solid state. We would need to add the enthalpy of sublimation, which would convert the solid into a gas. We would add this to the bonds broken, then we would calculate the mean bond enthalpies for bonds formed, then we have our answer.

Warda Sahib 2J
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Re: Sublimation

Postby Warda Sahib 2J » Mon Feb 12, 2018 7:00 pm

Enthalpy of Sublimation (solid to gas) is the sum of enthalpy of fusion and enthalpy of vaporization

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