Question

Phenol (Molecular Weight= 94.11 g/mol) is a low melting point solid used in DNA purifications. The molar heat of fusion of phenol is 11.5 kJ/mol. Calculate the heat required to melt 100.0 grams of phenol at its normal melting point.

Answer 1

As we know melting of solids occur at constant temperature and the heat utilised to melt one mole of solid is called the molar heat of fusion.

So we should begin by calculating the no. of moles of phenol in 100 grams of phenol.

           

           So, now that we know the no. of moles of phenol to be melted, we can take the product of Molar heat of fusion and the no. of moles of Phenol to calculate the heat required to melt the given amount of phenol.

          

Hence, Heat required to melt 100 grams of Phenol at normal temperature = 12.22 kJ.