Question

When backpacking in the wilderness, hikers often boil water to sterilize it for drinking. Suppose that you are planning a backpacking trip and will need to boil 38 Lof 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 0.78 g/mL; the initial temperature of the water is 25.0 ∘C; and the standard enthalpy of formation of C7H16 is -224.4 kJ/mol.

Express your answer using two significant figures.

Answer 1

Answer:

Given,

To determine the volume of fuel required

density of water = 1 g/ml,

volume = mass

Here heat required to bubble 38 g water

Now let us consider,

q = mCpdT

substitute values

q = 38 x 4.184 x (100-25)

q = 11.924 kJ

DeltaH vitality discharged per mole burning of C7H14 is 224.24 kJ/mol

15% = 224.24 x 15/100

= 33.66 kJ/mol

Now to compute the moles of C7H16 required to discharge 11.924 kJ of warmth heat

= 1 x 11.924/33.66

= 0.3542 moles

mass of fuel required = 0.3542 x 100.21

Mass = 35.49 g

Density = Mass/ Volume

Volume = Mass/Density

substitute values

Volume of fuel required = 35.49 / 0.78  

Volume = 45.50 ml