[填空题]
A constant mass of ideal gas expands at a constant pressure against a piston in a cylinder. During this process, the total thermal energy supplied to the gas is 810 J.
The following data are available.
The initial volume of the gas=$4.0\times10^{-4}\,m^3$
The final volume of the gas=$1.2\times10^{-4}\,m^3$
The pressure of the gas=$2.2\times10^{-4}\,m^3$
1.Explain how the equation for the First Law of Thermodynamics is an expression of conservation of energy.
2.Show that the work done by the gas during the expansion is about 180$\,J$ W= $J$
3.Calculate the change in internal energy of the gas and state whether it is an increase or decrease.ΔU= $J$
4.The number of the moles of the gas is 0.52 $\,mol$. Use your answer from (a)(iii), determine the temperature change.ΔT= $K$
2.The gas returns to its original state by following two specific thermodynamic processes. The cycle can be seen in the graph below.
During the thermal process from B to C, there is no exchange of heat between the system and the surroundings.
1.Identify the thermal processes on the graph.
A→ B:
B→ C:
C→ A:
2.For the process from B to C, deduce the change in entropy of the system.
3.Use the 1st law of thermodynamics to explain why the temperature of the gas increases during the process from B to C.
4.Explain whether the second law of thermodynamics is violated during the process from B to C.
