a) The following reaction occurs in an open beaker: C2H5OH (g) ---> C2H4(g) + H2O (g) {Bond Energy (kJ/mol): C-H = 415 ; C-C = 345 ; C-O = 350 ; O-H = 464 ; C=C = 611} i) Calculate the ΔH0rxn for this reaction from the given bond energies. kJ ii) Is this reaction an open, closed or isolated system? iii) Would you feel hot or cold if you were near this reaction when it occurred? This is because (choose from I - V) I. the reaction is exothermic and absorbs energy from the surroundings. II. the reaction is exothemic and releases energy to the surroundings. III. the reaction is endothermic and absorbs thermal energy from the surroundings. IV. the reaction is endothermic and loses heat to the surroundings. V. the reaction produces steam which contains a lot of heat.
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.
a) The following reaction occurs in an open beaker: C2H5OH (g) ---> C2H4(g) + H2O (g)
{Bond Energy (kJ/mol): C-H = 415 ; C-C = 345 ; C-O = 350 ; O-H = 464 ; C=C = 611}
i) Calculate the ΔH0rxn for this reaction from the given bond energies. kJ
ii) Is this reaction an open, closed or isolated system?
iii) Would you feel hot or cold if you were near this reaction when it occurred?
This is because (choose from I - V)
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I. the reaction is exothermic and absorbs energy from the surroundings.
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II. the reaction is exothemic and releases energy to the surroundings.
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III. the reaction is endothermic and absorbs thermal energy from the surroundings.
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IV. the reaction is endothermic and loses heat to the surroundings.
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V. the reaction produces steam which contains a lot of heat.
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