Question

Old fashion steam locomotives operated by boiling water and using the steam to drive a piston that moved the train. How much energy ( in MJ) is required to turn 824 gallons of water at 100 C into steam? The heat of fusion for water is 6.01 kJ/mol and the heat of vaporization is 40.7 kJ/mol. The units are MJ.

Answer 1

824 gallons x approx 3.8 L/gallon = approx 3000 L (but you need to use a better factor and not estimate as I've done.
Then 3000 L has a mass of about 3000 g.
q = mass H2O x heat vaporiation = ?
Note: If you use 40.7 kJ/mol you must use mass H2O in mol(which means convert from grams to mols), and the answer will come out in kJ. Convert to MJ.