Use the following values to answer each part. The specifi c heat of water is 1.00 cal/(g · °C); the heat of fusion of water is 79.7 cal/g; and the heat of vaporization of water is 540 cal/g. a. How much energy (in calories) is needed to melt 45 g of ice at 0.0 °C and warm it to 55 °C? b. How much energy (in calories) is released when 45 g of water at 55 °C is cooled to 0.0 °C, and frozen to solid ice at 0.0 °C? c. How much energy (in kilocalories) is released when 35 g of steam at 100. °C is condensed to water, the water is cooled to 0.0 °C, and the water is frozen to solid ice at 0.0 °C?
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.
Use the following values to answer each part. The specifi c
heat of water is 1.00 cal/(g · °C); the heat of fusion of water is
79.7 cal/g; and the heat of vaporization of water is 540 cal/g.
a. How much energy (in calories) is needed to melt 45 g of
ice at 0.0 °C and warm it to 55 °C?
b. How much energy (in calories) is released when 45 g of
water at 55 °C is cooled to 0.0 °C, and frozen to solid
ice at 0.0 °C?
c. How much energy (in kilocalories) is released when 35 g
of steam at 100. °C is condensed to water, the water is
cooled to 0.0 °C, and the water is frozen to solid ice at
0.0 °C?
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