Lightweight camping stoves typically use a mixture of Cs and C6 hydrocarbons, which is called white gas. Assuming white gas is 100% C5H12 (MW = 72.15 g/mol) with an enthalpy of combustion of –3550 kJ/mol, how many grams of it must be used to heat 1.50 L of water from 20.0°C to 80.0°C? Assume all the energy is used to heat the water. 8.96 g 9.65 g %3D d. 6.99 g 10.73 g а. е. b. с. 7.65 g
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
Molecular mass of C5H12 = 72.15g/mol
Enthalpy of combustion = -3550kJ/mol
Volume of water = 1.5L
Ti = 20°C
Tf = 80°C
We need to find the mass of C5H12 used to heat 1.5L water.
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