chemistry

Suppose that you are planning a backpacking trip and will need to boil 40 L of water for your group. What volume of fuel should you bring? Assume each of the following: the fuel has an average formula of C7H16; 15% of the heat generated from combustion goes to heat the water (the rest is lost to the surroundings); the density of the fuel is 0.78g/mL; the initial temperature of the water is 25.0C; and the standard enthalpy of formation of C7H16 is -224.4kJ/mol. Express your answer using two significant figures.