Homework #$3$: Properties, Processes, & Property Tables

Due Date: Monday, September $16$th at $11$:$59$PM

Submission Procedure: Please submit a PDF of your handwritten work via Gradescope.

Suggested Readings: $4\mathrm{.}1,4\mathrm{.}2,4\mathrm{.}3,4\mathrm{.}4,4\mathrm{.}5($Cengal$)$

Assignment Description: The purpose of this homework assignment is to practice the following

items:

Reading and interpreting the property tables $($Appendix A$)$ to determine thermodynamic prop$-$

erties at various states during a process

Plotting various thermodynamic states of a system undergoing any iso$-$ process using a T$-$v or

P$-$v property diagram

Using quality to determine specific volume of a saturated substance.

Performing linear interpolation on Property Table data.

Assignment Background

Properties of Systems: Every thermodynamic analysis requires us to analyze a system at any given

state. Our system, typically a liquid or gas, will undergo various processes which physically change

the thermodynamic properties $($i$.$e$.,$ change the state of our system$).$ Consider the piston$-$cylinder

device from Homework #$2$: at State $1,$ the system was initially at $T_1,P_1,$ and $v_1.$ Then, the system

underwent some process $($an isochoric process brought on by placing a burner underneath the device$).$

At the end of the isochoric process, we found that $v_2$ remained the same as $v_1$ but $P_2$ and $T_2$ had

increased. Since $T_2$ and $P_2$ were different from $T_1$ and $P_2$ respectively, we knew that State $2$ State

State Postulate: The State Postulate tells us that:

The state of a simple, compressible system is completely specified by two independent, in$-$

tensive properties.

This means that if we know $2$ independent, intensive thermodynamic properties, then we can determine

all of the other remaining properties at that state. To determine these other properties requires the

use of:

Equation of State $($Homework $2),$ or

Property Tables $($Homework $3)$

Phases of a Pure Substance: It is important to note that the selection of $2$ independent, intensive

properties boils down $($thermo joke$)$ to knowing the phase of the substance. Below is a table which

indicates appropriate thermodynamic property combinations that may set the state of a system as

a function of the phase. Notice that for any substance existing in a saturated state, we cannot

use pressure and temperature to define the state. When pure substances undergo phase change $($i$.$e$.,$

are saturated$),$ temperature and pressure become dependent properties. This means that when

temperature changes, pressure must also change.