( You are given the following data for butane, C4 H10 Normal melting point -138^∘ C Normal boili

step 1 So here we are asked to sketch the phase diagram of butane. So you can visit this website if you

( You are given the following data for butane, C4 H10 Normal...

( You are given the following data for butane, $\mathrm{C}_{4} \mathrm{H}_{10}$ Normal melting point $-138^{\circ} \mathrm{C}$ Normal boiling point $0^{\circ} \mathrm{C}$ Critical temperature $152^{\circ} \mathrm{C}$ Critical pressure 38 atm Assume that the triple point is slightly lower in temperature than the melting point and that the vapor pressure at the triple point is $3 \times 10^{-5}$ torr. (a) Sketch a phase diagram for butane. (b) Butane at 1 atm and $140^{\circ} \mathrm{C}$ is compressed to $40 \mathrm{~atm}$. Are two phases present at any time during this process? (c) Butane at 1 atm and $200^{\circ} \mathrm{C}$ is compressed to 40 atm. Are two phases present at any time during this process?

( You are given the following data for butane, $\mathrm{C}_{4} \mathrm{H}_{10}$
Normal melting point $-138^{\circ} \mathrm{C}$
Normal boiling point $0^{\circ} \mathrm{C}$
Critical temperature $152^{\circ} \mathrm{C}$
Critical pressure 38 atm
Assume that the triple point is slightly lower in temperature than the melting point and that the vapor pressure at the triple point is $3 \times 10^{-5}$ torr. (a) Sketch a phase diagram for butane. (b) Butane at 1 atm and $140^{\circ} \mathrm{C}$ is compressed to $40 \mathrm{~atm}$. Are two phases present at any time during this process? (c) Butane at 1 atm and $200^{\circ} \mathrm{C}$ is compressed to 40 atm. Are two phases present at any time during this process?

Key Concepts

Phase Diagram

A phase diagram is a graphical representation that shows the state (i.e., solid, liquid, or gas) of a substance under different conditions of temperature and pressure. It includes boundaries that indicate where phase transitions occur and highlights regions where multiple phases can coexist in equilibrium.

Triple Point

The triple point is the specific set of temperature and pressure conditions under which all three phases of a substance—solid, liquid, and gas—are in equilibrium. This point is fundamental in thermodynamics because it serves as a unique reference for defining temperature and pressure scales.

Critical Point

The critical point marks the end of the liquid-vapor boundary on a phase diagram. At conditions above the critical temperature and critical pressure, the distinction between liquid and vapor phases disappears, resulting in a single supercritical fluid phase. This concept is crucial for understanding the behavior of substances under extreme conditions.

Phase Transitions

Phase transitions involve the change of a substance from one state of matter to another, such as melting, boiling, or sublimation. These transitions occur when the substance crosses phase boundaries on a phase diagram, and they are typically associated with changes in properties like density and enthalpy.

Vapor Pressure

Vapor pressure is the pressure exerted by a vapor in equilibrium with its condensed phases (solid or liquid) at a given temperature. It is a key parameter in determining a substance’s boiling point and plays an essential role in phase equilibria, particularly near phase boundaries.

Compression Process

The compression process refers to the change in pressure of a substance, which may drive it across different regions of the phase diagram. During compression, depending on the temperature and the substance’s path through the phase diagram, the system may cross a two-phase region, temporarily exhibiting a mixture of phases as it undergoes a phase transition.

Transcript

00:01 So here we are asked to sketch the phase diagram of butane.

00:05 So you can visit this website if you want to see an actual one that has different units.

00:12 But here is my sketch of the phase diagram.

00:16 So we are told that we have the normal melting point and normal boiling point.

00:22 That is the melting point and boiling point at one atmosphere.

00:27 Melting point is when we go from solid to liquid.

00:29 So we'll label one atmosphere on the y -axis for pressure.

00:36 And we'll go over here, wherever it crosses the line from solid to liquid, that is the normal melting point.

00:44 And then we have the normal boiling point.

00:45 So basically, we start at one atmosphere, and then we move over to this line, and the normal boiling point is zero degrees celsius.

00:54 So we have a critical temperature and critical pressure that is just the point when we not.

01:00 Longer have separate liquid and gas phases.

01:04 So we have 38 atmosphere and 152 degrees celsius and that's just going to be this point here, right where this line between liquid and gas has.

01:18 So the triple point is slightly lower in temperature than the melting point, which makes sense.

01:22 The triple point is here when all phases exist and that's a little bit lower than this.

01:27 We have the vapor pressure at the triple point in tor, so i converted that to atmosphere.

01:32 In order to do that, when atmosphere is equal to 760 tor, divide by...

01:38 760 and you're able to get the pressure in atmospheres.

01:43 So now that's our sketch.

01:45 So for b, we are told bution at one atmosphere and 140 degrees celsius is compressed to 40 atmospheres.

01:52 We want to know our two phases present at any time...

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