Final answer:
The heat energy required to melt 649.2 g of HBr is 19.35 kJ, calculated by converting the mass to moles and multiplying by the molar heat of fusion.
Step-by-step explanation:
To calculate the amount of heat energy required to melt 649.2 g of HBr, you first need to convert the mass of HBr to moles. The molar mass of HBr (Hydrogen bromide) is approximately 80.9 g/mol. As we have 649.2 g of HBr, we do the following calculation:
649.2 g HBr × (1 mol HBr / 80.9 g HBr) = 8.03 mol HBr.
Next, you multiply the number of moles of HBr by the molar heat of fusion to find the total heat energy needed:
8.03 mol HBr × 2.41 kJ/mol = 19.35 kJ.
Therefore, the amount of heat energy required to melt 649.2 g of HBr is 19.35 kJ. This enthalpy of fusion is an endothermic process, meaning it absorbs heat from the surroundings.