If the heat of fusion of water is 80.9 cal/g, how many calories are needed to melt 45.0 g of ice at 0 degree C?
The heat of fusion of water is 80.9 calories per gram. To melt each gram of ice to liquid water 80.9 calories are required.
To melt 45 g of ice at 0 degree C, the number of calories required is given by 45*80.9 = 3640.5.
The required heat to melt 45 g of ice is 3640.5 calories.