Chapter 6, Problem 6.69P

Interpretation Introduction

(a)

Interpretation:

The pressure at which the first vapor bubble is formed along with its composition is to be determined.

Concept introduction:

Bubble-point pressure is the pressure at which first bubble of vapor appears when a liquid is decompressed at a constant temperature. At this point vaporization starts.

Using a $P_{xy}$ diagram, the Vapor−liquid equilibrium calculations for binary systems can be considerably simplified. The plot of the equilibrium pressure versus the mole fraction of the more volatile component of the two along with the curves being drawn for both the liquid phase and the vapor phase at constant temperature, constitutes the $P_{xy}$ diagram.

Interpretation Introduction

(b)

Interpretation:

The pressure at which the last drop of liquid evaporates along with its composition is to be determined.

Concept introduction:

Dew-point pressure is the pressure at which last drop of liquid evaporates when a liquid mixture is decompressed at a constant temperature. At this point vaporization is completed.

Using a $P_{xy}$ diagram, the Vapor−liquid equilibrium calculations for binary systems can be considerably simplified. The plot of the equilibrium pressure versus the mole fraction of the more volatile component of the two along with the curves being drawn for both the liquid phase and the vapor phase at constant temperature, constitutes the $P_{xy}$ diagram.

Interpretation Introduction

(c)

Interpretation:

The equilibrium composition of the liquid and vapor mixture are to be calculated when the pressure of the cylinder is $750\text{ mmHg}$. Also, the ratio of moles of vapor to the moles of liquid at this point is to be calculated.

Concept introduction:

Using a $P_{xy}$ diagram, the Vapor−liquid equilibrium calculations for binary systems can be considerably simplified. The plot of the equilibrium pressure versus the mole fraction of the more volatile component of the two along with the curves being drawn for both the liquid phase and the vapor phase at constant temperature, constitutes the $P_{xy}$ diagram.

A flowchart is the complete representation of a process through boxes or other shapes which represents process units and arrows that represents the input and output of the process. The flowchart must be fully labelled to infer important data about the process involved.

In a system, a conserved quantity (total mass, mass of a particular species, energy or momentum) is balanced and can be written as:

$input+generation-output-consumpumtion=accumulation$

Here, ‘input’ is the stream which enters the system. ‘generation’ is the term used for the quantity that is produced within the system. ‘output’ is the stream which leaves the system. ‘consumption’ is the term used for the quantity that is consumed within the system. ‘accumulation’ is used for the quantity which is builds up within the system.

All the equations which are formed are then solved simultaneously to calculate the values of the unknown variables.

Interpretation Introduction

(d)

Interpretation:

The volume of the cylinder contents is to be calculated at pressures, $1000\text{ mmHg, 750 mmHg and 600 mmHg}$.

Concept introduction:

The volume $\left(V_{\text{m}}\right)$ of a mixture is calculated as:

$V_{\text{m}}=\sum _i\frac{n_i{\left(\text{MW}\right)}_i}{{\rho }_i}$

             …… (3)

Here, $n_i$ is the moles, ${\left(\text{MW}\right)}_i$ is the molecular weight and ${\rho }_i$ is the density of the species $i$.

Equation of states for an ideal gas is:

$PV=nRT$

             …… (4)

Here, $P$ is the pressure of the gas, $V$ is the volume of the gas, $n$ is the moles of the gas, $T$ is the temperature of the gas and $R$ is the universal gas constant.