5.00 × 10−2 mol KOH and an excess of hydrochloric acid are combined in 100.0 mL of water initially at 25.0 °C, leading to a final measured temperature of 31.1 °C. (a) What is the heat flow for the water in the calorimeter, qH2O, in Joules? (b) Assuming the calorimeter constant Ccal = 50.0 J °C , what is the heat flow for the calorimeter, qcal, in Joules? (c) What is the amount of heat given off by the reaction, qrxn, in Joules? (d) What is the molar enthalpy of the neutralization reaction (shown below) as measured in the calorimeter, ∆H◦ rxn in kilojoules per mole?
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.
5.00 × 10−2 mol KOH and an excess of hydrochloric acid are combined in 100.0 mL of water initially at 25.0 °C, leading to a final measured temperature of 31.1 °C.
(a) What is the heat flow for the water in the calorimeter, qH2O, in Joules?
(b) Assuming the calorimeter constant Ccal = 50.0 J °C , what is the heat flow for the calorimeter, qcal, in Joules?
(c) What is the amount of heat given off by the reaction, qrxn, in Joules?
(d) What is the molar enthalpy of the neutralization reaction (shown below) as measured in the calorimeter, ∆H◦ rxn in kilojoules per mole?
H3O + (aq) + OH– (aq) → 2H2O (l)
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