In this assignment, we will consider 1 mole of N2(g) which is in a closed container. In state 1, the temperature is 25°C and the pressure in the container is 10 bar. We assume that N2 behaves like an ideal gas and that Cp,m(g) = 29.125 J mol-1K-1, and is independent of temperature. 1) How large will a) the volume work, b) the heat and c) the change in enthalpy of N2 be if, starting from state 1, the volume of the container was changed in a reversible and isothermal manner so that the pressure in the container drops to 1 bar?
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.
In this assignment, we will consider 1 mole of N2(g) which is in a closed container. In state 1, the temperature is 25°C and the pressure in the container is 10 bar.
We assume that N2 behaves like an ideal gas and that Cp,m(g) = 29.125 J mol-1K-1, and is independent of temperature.
1) How large will a) the volume work, b) the heat and c) the change in enthalpy of N2 be if, starting from state 1, the volume of the container was changed in a reversible and isothermal manner so that the pressure in the container drops to 1 bar?
2) How big will a) the volume work, b) the heat and c) the change in enthalpy of N2 be if, again starting from state 1, the volume of the container was changed in a reversible and adiabatic way so that the pressure in the container drops to 1 bar?
3)
a) Explain what reversible means in tasks 1) and 2)
b) state what the change in the entropy of the universe is in tasks 1) and 2).
4) How large will a) the volume work, b) the heat and c) the change in enthalpy of N2 be if, in state 1, the external pressure was suddenly changed to 1 bar and afterwards the volume of the container was allowed to adjust isothermally to the changed but constant external pressure?
5) What is the change in the entropy of the universe in problem 4?
According to question, N2 is behaving as an ideal gas.
According to question, initial pressure P1 = 10 bar = 10 x 0.987 atm = 9.87 atm
initial volume V1
initial temperature T1 = 25oc = 298 K
According to ideal gas equation,
P1 x V1 = nRT1
9.87 atm x V1 = 1mole x 0.082 L atm mole-1 K-1 x 298 K
V1 = 2.475 L
It will undergo a reversible isothermal process. So temperature T2 = 25oc = 298K
final pressure P2 = 1 bar = 1 x 0.987 atm = 0.987 atm
According to ideal gas equation,
P2 x V2 = nRT2
a) volume work:
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