Question

The molar heat of fusion of platinum (Pt) is 4.700 kcal/mol. How much heat must be added to 85.5 g of solid platinum at its melting point to completely melt it?

Answer 1

The heat required to completely melt the given substance, platinum, we just have to convert first the given mass in mole and multiply the answer to its molar heat of fusion.. 
                              Hf  = mass x (1/molar mass) x molar heat of fusion
                            Hf = (85.5 g) x (1 mole/195.08 g) x 4.70 kcal/mol
                                   Hf = 2.06 kcal

Answer 2

the answer is 2.06 kcal