Answer:
2.104 L fuel
Explanation:
Given that:
Volume of water = 35 L = 35 × 10³ mL
initial temperature of water = 25.0 ° C
The amount of heat needed to boil water at this temperature can be calculated by using the formula:
where
specific heat of water c= 4.18 J/g° C
Also; Assume that the fuel has an average formula of C7 H16 and 15% of the heat generated from combustion goes to heat the water;
thus the heat of combustion can be determined via the expression
For heptane; the equation for its combustion reaction can be written as:
The standard enthalpies of the products and the reactants are:
Therefore; the standard enthalpy for this combustion reaction is:
This simply implies that the amount of heat released from 1 mol of C7H16 = 4466.1 kJ
However the number of moles of fuel required to burn heat released is:
Since number of moles = mass/molar mass
The mass of the fuel is:
Given that the density of the fuel is = 0.78 g/mL
and we know that :
density = mass/volume
therefore making volume the subject of the formula in order to determine the volume of the fuel ; we have
volume of the fuel = mass of the fuel / density of the fuel
volume of the fuel =
volume of the fuel = 2.104 L fuel