The thermochemical equation for the combustion of methanol is CH3OH (g) + 3/2 O2(g) → CO2(g) + 2 H2O(l) ΔH = -764 kJ mol-1 How many kJ of heat are produced when 5.00 g of methanol reacts with excess oxygen gas as shown in the equation? (molar mass of methanol, CH3OH: 32.05 g mol-1) a. 4.77 kJ b. 153 kJ c. 764 kJ d. 3820 kJ e. 119 kJ
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.
The thermochemical equation for the combustion of methanol is
CH3OH (g) + 3/2 O2(g) → CO2(g) + 2 H2O(l) ΔH = -764 kJ mol-1
(molar mass of methanol, CH3OH: 32.05 g mol-1)
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