13. Liquids, Solids & Intermolecular Forces

Phase Diagrams

Phase Changes, Heats of Fusion and Vaporization, and Phase Diagrams

Arrow I corresponds to:<img src="https://static.studychannel.pearsonprd.tech/courses/general-chemistry/thumbnails/images/02a9b783"class="fr-fic fr-dii">

Water at room temperature is placed in a flask connected by rubber tubing to a vacuum pump, and the pump is turned on. After several minutes, the volume of the water has decreased, and what remains has turned to ice. Explain

What are phase diagrams? - Real Chemistry

 This value is the amount of energy required just to heat the ice from &#x2212;12.0&#x2103; to the melting point.   Other processes are involved. 

 There are three distinct processes involved each requires a separate calculation:  heating ice, melting ice and heat liquid water. 

 This value is the amount of energy required just to melt the ice at the melting point.   Other processes are involved. 

 This value is the amount of energy required just to heat the water from the melting point to 88.0&#x2103;. Other processes are involved. 

 Correct, you took into consideration all three processes involved. 

 There are three segments that contribute to the overall heat required: (1) the heating of the ice before it melts, (2) melting the ice, and (3) heating the water. 

Calculate the amount of heat (in J) required to heat 2.00 grams of ice from &#x2212;12.0&#x2103; to 88.0&#x2103;. The heat of fusion of water is 6.02 kJ/mol, the specific heat capacity of ice is 2.09 J/g &#9642;&#x2103; and the specific heat capacity of water is 4.184 J/g &#9642;&#x2103;.

States of Matter of Phase Diagrams

Phase Diagrams Example 1

The table below lists the density of O2 at various tempera-tures and at 1 atm. The normal melting point of O2 is 54 K. <img src="https://lightcat-files.s3.amazonaws.com/problem_images/3a437fe05c17d4c0-1665680342081.jpg" alt="" /> (b) Over what temperature range is O2 a liquid?

&#916;Hfreezing &lt; &#916;Hfus

 The enthalpy involved in freezing and fusion (melting) are the same magnitude but opposite in sign. 

&#916;Hsub = &#916;Hfus + &#916;Hvap

 Correct, sublimation involves a solid directly forming the vapor (gas) state. 

&#916;Hvap &lt; &#916;Hfus

 The enthalpy of vaporization is always greater than the corresponding enthalpy of fusion. 

&#916;Hsub < &#916;Hvap

 The enthalpy of sublimation is always greater than the corresponding enthalpy of vaporization. 

 Consider the changes of state representing by each type of enthalpy change. 

Liquid butane (C4H10) is stored in cylinders to be used as a fuel. The normal boiling point of butane is listed as -0.5 °C. (b) Suppose the valve to the tank is opened and a few liters of butane are allowed to escape rapidly. What do you expect would happen to the temperature of the remaining liquid butane in the tank? Explain.

Appendix B lists the vapor pressure of water at various external pressures. (c) A city at an altitude of 5000 ft above sea level has a barometric pressure of 633 torr. To what temperature would you have to heat water to boil it in this city? <img src="https://lightcat-files.s3.amazonaws.com/problem_images/d6e0f91e60ad1f29-1665759547079.jpg" alt="" />

 Correct the line defining melting points is crossed between “a” and “b.” 

 Think about the fact that higher temperatures and lower pressures favor the liquid state. 

 Determine the physical state of the substance at point “a” and at point “b” to determine the phase change occurring. 

Consider the phase diagram below: <img src="https://media.pearsoncmg.com/ph/esm/esm_tro_chemistry_6/msa/content/practice-quiz/img/troama5_pq_c12q15.png" alt= "Phase diagram showing the letter 'a' located in the region of the phase diagram on the upper left. The letter 'b' is located in the region of the phase diagram on the upper right. An arrow connects 'a' to 'b' with the arrow head pointing to 'b'." class="block" />What changes would the sample undergo as the sample moves from the temperature and pressure at point “a” to the temperature and pressure at point “b”?

At standard temperature and pressure, the molar volumes of Cl2 and NH3 gases are 22.06 and 22.40 L, respectively. (d) Are the molar volumes in the solid state as similar as they are in the gaseous state? Explain.

A phase diagram for a substance that exhibits the liquid
crystalline state is shown. 
(b) If the substance is at a temperature and pressure repre- sented by point 1 and the temperature is increased until the phase changes, what is the phase transition? Describe how the ordering of molecules changes, and propose a reason for the change.<img src="https://lightcat-files.s3.amazonaws.com/problem_images/1a4f9cf5b642a665-1671374197111.jpg" alt="" />

Nitrogen has a normal boiling point of 77.3 K and a melting point 
(at 1 atm) of 63.1 K. Its critical temperature is 126.2 K and its 
critical pressure is 2.55 * 104 torr. It has a triple point at 63.1 K 
and 94.0 torr. Sketch the phase diagram for nitrogen. Does 
nitrogen have a stable liquid state at 1 atm?

The phase diagram of a hypothetical substance is <img src="https://lightcat-files.s3.amazonaws.com/problem_images/80b051a35272520c-1665679882549.jpg" alt="" /> (b) What is the physical state of the substance under the following conditions? (i) T = 150 K, P = 0.2 atm; (ii) T=100K,P=0.8atm; (iii) T = 300K,P = 1.0atm. [Section 11.6]

The following phase diagram shows part of the liquid–vapor phase-transition boundaries for two solutions of equal con- centration, one containing a nonvolatile solute and the other containing a volatile solute whose vapor pressure at a given temperature is approximately half that of the pure solvent. <img src="https://lightcat-files.s3.amazonaws.com/problem_images/43765f28daf99436-1671643678498.jpg" alt="" /> (d) Based on your drawing, what is the approximate normal boiling point of the pure solvent?

(a)Two pans of water are on different burners of a stove.One pan of water is boiling vigorously, while the other is boiling gently. What can be said about the temperature of the water in the two pans?

You are high up in the mountains and boil water to make some tea. However, when you drink your tea, it is not as hot as it should be. You try again and again, but the water is just not hot enough to make a hot cup of tea. Which is the best explanation for this result? (a) High in the mountains, it is probably very dry, and so the water is rapidly evaporating from your cup and cooling it. (b) High in the mountains, it is probably very windy, and so the water is rapidly evapo- rating from your cup and cooling it. (c) High in the moun- tains, the air pressure is significantly less than 1 atm, so the boiling point of water is much lower than at sea level. (d) High in the mountains, the air pressure is significantly less than 1 atm, so the boiling point of water is much higher than at sea level.

 Polarizability relates to how easily a charge separation can be made to occur. 

 Viscosity describes the resistance of a liquid to flow. 

 Dynamic equilibrium occurs when some forward change is occurring at the same rate as the reverse change. 

 Correct, the compounds are said to be miscible. 

 Compressibility has to do with the ability of a substance to change its volume usually due to pressure changes. 

 This terms relates the ability of two liquids to homogenously mix in all proportions. 

 The ability for liquids to mix without separating into two phases is called _________. 

 The changes between the solid and gas and the liquid and gas state are also involved. 

 melting, freezing, vaporization, and condensation  

 The changes between the solid and gas state are also involved. 

 melting, freezing, sublimation, and deposition 

 The changes between the gas and liquid state are also involved. 

 vaporization, condensation, sublimation, and deposition 

 The changes between the solid and liquid state are also involved. 

 melting, freezing, vaporization, condensation, sublimation, and deposition 

 Correct, the changes among all three phases of matter are involved at this point. 

 The triple point represents a unique set of conditions at which the three phases are equally stable and in equilibrium. 

 Which processes occur at the triple point? 

Benzene has a melting point of 5.53 °C and a boiling point of 80.09 °C at atmospheric pressure. Its density is0.8787 g>cm3 when liquid and 0.899 g>cm3 when solid; it has Tc = 289.01 °C, Pc = 48.34 atm, Tt = 5.52 °C, and Pt = 0.0473 atm. Starting from a point at 200 K and
66.5 atm, trace the following path on a phase diagram. (1) First, increase T to 585 K while keeping P constant.
(2) Next, decrease P to 38.5 atm while keeping T constant.
(3) Then, decrease T to 278.66 K while keeping P constant.
(4) Finally, decrease P to 0.0025 atm while keeping T
constant.
What is your starting phase, and what is your final phase?

Consider the phase diagram shown here. Identify the states
present at points a through g.
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/3ce48b7aa91111e9-1659629481794.jpg" alt="" />

Naphthalene (C10H8) is the main ingredient in traditional mothballs. Its normal melting point is 81 °C, its normal boiling point is 218 °C, and its triple point is 80 °C at 1000 Pa. Using the data, construct a phase diagram for naphthalene, labeling all the regions of your diagram.

Based on the phase diagram of CO2 shown in Figure 11.39(b),
describe the state changes that occur when the temperature of
CO2 is increased from 190 K to 350 K at a constant pressure of
(a) 1 atm<img src="https://lightcat-files.s3.amazonaws.com/problem_images/b1e7332e43c5b331-1659631687736.jpg" alt="" />

Using the vapor-pressure curves in Figure 11.25, (d) estimate the external pressure at which diethyl ether will boil at 40 °C.<img src="https://lightcat-files.s3.amazonaws.com/problem_images/ed9abce22edcd796-1665759286398.jpg" alt="" />

11.2 Phase Diagrams | General Chemistry

What is the normal freezing point of this unknown substance?<img src="https://static.studychannel.pearsonprd.tech/courses/general-chemistry/thumbnails/images/5db17422"class="fr-fic fr-dii"style="width:350px;">

The Phase Diagram of Water

Substance X has a vapor pressure of 100 mm Hg at its triple point (48 °C). When 1 mol of X is heated at 1 atm pres- sure with a constant rate of heat input, the following heating curve is obtained: 
(b) For each of the following, choose which phase of X (solid, liquid, or gas) fits the description.
(iii) Has the greatest specific heat<img src="https://lightcat-files.s3.amazonaws.com/problem_images/9425f2e42f0a71a9-1671416708378.jpg" alt="" />

The phase diagram for sulfur is shown here. The rhombic and
monoclinic states are two solid states with different structures.
b. Which of the two solid states of sulfur is more dense?
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/737378fe7c6bdd9b-1659632341923.jpg" alt="" />

Assume that you have a sample of gas at 350 K in a sealed
container, as represented in (a). Which of the drawings
(b)–(d) represents the gas after the temperature is lowered
from 350 K to 150 K? The boiling point of the gas is 90 K.
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/c72ce85069c6afe9-1669229036674.jpg" alt="" />

Phase diagrams | States of matter and intermolecular forces | Chemistry | Khan Academy

 Heating the initial sample to its melting point. 

 This change involves increasing the kinetic energy of the molecules and therefore involves a change in temperature. 

 Heating the sample and converting the liquid to the gas at the boiling point. 

 Correct, the added thermal energy involves an increase in the potential energy of the molecules which does not affect temperature. 

 Heating the liquid at the melting point to the liquid at the boiling point. 

 Heating the gas above the boiling point. 

 Phase transitions involve changes in potential energy. 

 Consider adding enough heat to a solid sample of a substance below its melting point to change the sample to the gas above its boiling point.  Which of the following would involve no change in temperature of the sample as the described transition occurs? 

Phase Diagrams Concept 2

Referring to Figure 11.29, describe the phase changes (and the temperatures at which they occur) when CO2 is heated from -80 to -20°C at (a) a constant pressure of 3 atm,<img src="https://lightcat-files.s3.amazonaws.com/problem_images/de7a0651c1d203ac-1665764281194.jpg" alt="" />

Phase Diagrams of Water & CO2 Explained -  Chemistry - Melting, Boiling & Critical Point

Using this graph of CS2 data, <img src="https://lightcat-files.s3.amazonaws.com/problem_images/344f94f8de9cabc8-1665757877570.jpg" alt="" /> determine (a) the approximate vapor pressure of CS2 at 30°C,

Phase Diagrams Example 2

(b) Could you measure the triple point of water by measuring the temperature in a vessel in which water vapor, liquid water, and ice are in equilibrium under 1 atm of air? Explain.

The critical point of this substance occurs at what temperature?<img src="https://static.studychannel.pearsonprd.tech/courses/general-chemistry/thumbnails/images/be1f4143"class="fr-fic fr-dii"style="width:395px;">

Use the phase diagram of neon to answer the following questions. (b) What can you say about the strength of the intermolecular forces in neon and argon based on the critical points of Ne and Ar (see Table 11.5.)?<img src="https://lightcat-files.s3.amazonaws.com/problem_images/2ba78e2e12fe035a-1665762015994.jpg" alt="" />

At 25 °C gallium is a solid with a density of 5.91 g/cm3. Its melting point, 29.8 °C, is low enough that you can melt it by holding it in your hand. The density of liquid gallium just above the melting point is 6.1 g/cm3. Based on this information, what unusual feature would you expect to find in the phase diagram of gallium?

The following compound undergoes a phase transition from the solid to the smectic liquid crystal phase at 121 °C. Upon further heating, the compound undergoes another transition to liquid phase at 131 °C. <img src="https://lightcat-files.s3.amazonaws.com/problem_images/65d4dfc6ccae5546-1671380085224.jpg" alt="" />
(a) Which image represents the arrangement of molecules at 125 °C?

The phase diagram for neon is <img src="https://lightcat-files.s3.amazonaws.com/problem_images/fde71d7b9309ab6d-1674841752116.jpg" alt="" /> Use the phase diagram to answer the following questions. (a) What is the approximate value of the normal melting point?

This portion of a phase diagram shows the vapor–pressure
curves of a volatile solvent and of a solution of that solvent
containing a nonvolatile solute. 
(b) What are the normal boiling points of the
solvent and the solution? [Section 13.5]
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/3616a93d4b038285-1665763694754.jpg" alt="" />

At what temperature can we no longer tell the difference between the liquid and gas phases?<img src="https://static.studychannel.pearsonprd.tech/courses/general-chemistry/thumbnails/images/d7fba098"class="fr-fic fr-dii"style="width:394px;">

A particular liquid crystalline substance has the phase diagram shown in the figure. By analogy with the phase diagram for a nonliquid crystalline substance, identify the phase present in each area. <img src="https://lightcat-files.s3.amazonaws.com/problem_images/f508b088ea45bf82-1665763002346.jpg" alt="" />

Draw a phase diagram showing how the phase boundaries differ for a pure solvent compared with a solution.<img src="https://lightcat-files.s3.amazonaws.com/problem_images/39f19845a375c000-1671424933334.jpg" alt="" /><img src="https://lightcat-files.s3.amazonaws.com/problem_images/4032e918d63a2dea-1671424965752.jpg" alt="" /><img src="https://lightcat-files.s3.amazonaws.com/problem_images/c6105f2c2f644dee-1671425212294.jpg" alt="" />

Argon has a normal boiling point of 87.2 K and a melting point 
(at 1 atm) of 84.1 K. Its critical temperature is 150.8 K and its 
critical pressure is 48.3 atm. It has a triple point at 83.7 K and 
0.68 atm. Sketch the phase diagram for argon. Which has the 
greater density, solid argon or liquid argon?

The phase diagram for sulfur is shown here. The rhombic and
monoclinic states are two solid states with different structures.
a. Below what pressure does solid sulfur sublime?
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/241868b62b3d64aa-1674596200421.jpg" alt="" />

Benzoic acid, C6H5COOH, melts at 122 °C. The density in the liquid state at 130 °C is 1.08 g/cm3. The density of solid benzoic acid at 15 °C is 1.266 g/cm3. (b) If you converted a cubic centimeter of liquid benzoic acid into a solid, would the solid take up more, or less, volume than the original cubic centimeter of liquid?

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Chad's Prep

1. Intro to General Chemistry

2. Atoms & Elements

3. Chemical Reactions

4. BONUS: Lab Techniques and Procedures

5. BONUS: Mathematical Operations and Functions

6. Chemical Quantities & Aqueous Reactions

7. Gases

8. Thermochemistry

9. Quantum Mechanics

10. Periodic Properties of the Elements

11. Bonding & Molecular Structure

12. Molecular Shapes & Valence Bond Theory

14. Solutions

15. Chemical Kinetics

16. Chemical Equilibrium

17. Acid and Base Equilibrium

18. Aqueous Equilibrium

19. Chemical Thermodynamics

20. Electrochemistry

21. Nuclear Chemistry

22. Organic Chemistry

23. Chemistry of the Nonmetals

24. Transition Metals and Coordination Compounds

[BOOK CHEM] Clutch Version

Body Centered Cubic Unit Cell

Body Centered Cubic Unit Cell contains 2 atoms total.

Phase&nbsp;Diagrams show&nbsp;what&nbsp;effect&nbsp;temperature and pressure have&nbsp;on a pure substance in a closed system without any air.

Intermolecular Forces and Physical Properties

Intermolecular forces influence physical properties. &nbsp;We will look at direct and indirect relationships.

Face Centered Cubic Unit Cell

Face Centered Cubic Unit Cell contains 4 atoms in total.

Heating and Cooling Curves

Heating and Cooling Curves represent amount of heat (q) absorbed or released by a substance during phase changes.

Clausius-Clapeyron Equation

The Clausius-Clapeyron Equation establishes a quantitative relationship between vapor pressure and temperature.&nbsp;

Molecular Polarity

Polarity of chemical bonds happen in molecules when there is an unequal sharing of electrons.&nbsp;

Intermolecular Forces

Intramolecular Forces are the bonding forces within a molecule. Intermolecular Forces are the attractive forces between 2 molecules.

Simple Cubic Unit Cell

Simple Cubic Unit Cell is the least complex&nbsp;cubic unit cell and contains only 1 atom.

Atomic, Ionic, and Molecular Solids

<div dir="auto"><div contenteditable="true"dir="auto"spellcheck="true">Crystalline solids represent structures with well-organized patterns and shapes. Amorphous solids represent structures that lack an organized pattern or shape.&nbsp;</div></div>

Crystalline Solids

Crystalline Solids are composed of unit cells, crystal lattice and lattice point.