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Methanol (CH3OH) has a heat of fusion of 3.16 kJ/mol. Which of the following is the heat of solidification that occurs when 63 grams of liquid methanol freezes?

Rodney Fox

in Chemistry

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Dana Keller on January 28, 2019

The heat of fusion and the solidifitation heat have the same magnitude.The difference is that when the substances melt are gaining (absorption) of heat, and when they freeze (solidify) the loss of heat release.The amount of heat that is 3.16 kJ/mol and it is necessary to determine the amount of substance (methanol) freezes.Divide the 63 grams of CH3OH by the molar mass of CH3OH to find the number of moles of CH3OH.The Molar mass of methanol = 12 g/mol + 4*1 g/mol + 16 g/mol = 32 g/mol=> number of moles = 63 g / (32 g / mol) = 1.969 mol ≈ 2.0 mol Now, the total heat = specific heat molar * number of moles=> total heat = 3.16 kJ/mol * 2.0 mol = 6.32 kJ Given that the CH3OH is the freezing of the heat release, and the convention is that the heat released is considered negative.Then, the final answer is - 6.32 kJ


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