Answer:
3.657 kg
Explanation:
Given:
Enthalpy of combustion of hard coal = -35 kJ/g
Enthalpy of combustion of gasoline = 1.28 × 10⁵ kJ/gal
Density of gasoline = 0.692 g/mL
now,
The heat provide 1 gallon of gasoline provide = 1.28 × 10⁵ kJ
and,
heat provided by the 1 gram of coal = 35 kJ
or
1 kJ of heat is provided by (1/35) gram of hard coal
therefore,
For 1.28 × 10⁵ kJ of heat, mass of hard coal = 1.28 × 10⁵ kJ × (1 / 35)
or
For 1.28 × 10⁵ kJ of heat, mass of hard coal = 3657.14 grams = 3.657 kg