Five moles of water with a temperature of 50 ° C are placed in a refrigerator with a temperature of 3 ° C. Calculate entropy change "for the system and its surroundings. (C for water is = 75.3 JK'mol 'and is independent of temperature.)
Answers
Answer:
with the temperature in Kelvin. Since entropy changes are much smaller than enthalpy changes, they are usually reported in J K–1 mol–1.
Examples of reversible processes are
Boiling: As temperature is constant, ΔS = ΔHvap/T
Melting: As temperature is constant, ΔS = ΔHfus/T
For many realistic applications, the surroundings are vast in comparison to the system. In such cases, the heat gained or lost by the surroundings as a result of some process represents a very small, nearly infinitesimal, fraction of its total thermal energy. For example, combustion of a fuel in air involves transfer of heat from a system (the fuel and oxygen molecules undergoing reaction) to surroundings that are infinitely more massive (the earth’s atmosphere). As a result, qsurr is a good approximation of qrev , and the second law may be stated as the following:
ΔSuniv=ΔSsys+ΔSsurr=ΔSsys+qsurrT(18.4.2)
We may use this equation to predict the spontaneity of a