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Postby 205154661_Dis2J » Sun Feb 09, 2020 11:37 pm

For 4C7, I know we calculated the enthalpy of vaporization for part b by turning 22.45g of ethanol into moles (which gives you 0.48), and then dividing 21.2kJ of energy by 0.48. This, in turn gives you 44.16 for the enthalpy of vaporization but I do not understand the question conceptually. Why are we dividing the energy by moles?

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Re: 4C7

Postby nicolely2F » Sun Feb 09, 2020 11:54 pm

The formula for enthalpy change is ΔH(vaporization) = q / n, which gives an answer of energy units per moles. This is because enthalpy of phase change measures the energy required to take 1 mole of some substance from one state to the other.

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