5. A 1.058-g sample of benzoic acid (HC;H;O2) is completely combusted in a "bomb" calorimeter, and the temperature of the calorimeter increases from 21.50°C to 28.45°C. The calorimeter contains 750.0 g of water (specific heat = 4.184 J/g.°C) and the "bomb“ has heat capacity of 890. J°C. Calculate: (a) the amount of heat (in kJ) absorbed by water; (b) the amount of heat (in kJ) absorbed by the "bomb"; (c) the total amount of heat (in kJ) produced by the combustion of benzoic acid sample, and (d) the molar enthalpy of combustion (AHcomb; in kJ/mol) of benzoic acid. (Answer: (a) 21.8 kJ; (b) 6.19 kJ; (c) -28.0 kJ; (d) AH.comb = -3.23 x 10° kJ/mol)
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.
calculate (d) the molar enthalpy of combustion (AHcomb; in kJ/mol) of benzoic acid.
I just need to understand how to calculate part d) the molar enthalpy of benzoic acid.
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