Question 1

Which of the following is most likely to have the highest viscosity at 25°C?

Accepted Answer

HOCH₂CH₂OH (ethylene glycol) has strong hydrogen bonding due to its two hydroxyl groups, leading to higher viscosity compared to the other compounds listed.

Question 2

What phases can be present at 200°C and 0.75 atm pressure?

Accepted Answer

The answer of What phases can be present at 200°C...

Question 3

When a liquid is heated at its boiling point,the

Accepted Answer

At the boiling point, the temperature of the liquid remains constant as long as any liquid is present because the heat energy is being used to convert the liquid into the gaseous state (vaporization). Once all the liquid has been converted into vapor, any additional heat will raise the temperature of the vapor phase. The other options are incorrect as ionic bonds are not present in all types of liquids, the temperature of the liquid does not decrease at its boiling point, and the temperature of the vapor phase increases as more heat is added.

Question 4

How much heat (kJ)is required to convert 3.12 moles of liquid benzene at 75.1°C to gaseous benzene at 115.1°C? The following information may be useful. b.p = 80.1ᴼC C_m(liquid benzene)= 136.0 J/ (mol * °C) ΔH_vap = 30.72 kJ/mol C_m(gaseous benzene)= 36.6 J/ (mol * °C)

Accepted Answer

To calculate the total heat required, we need to consider three steps: heating the liquid benzene from 75.1°C to its boiling point (80.1°C), vaporizing the liquid benzene at its boiling point, and then heating the gaseous benzene from 80.1°C to 115.1°C. 1. Heating the liquid benzene to its boiling point:$$ q_1 = m \cdot C_{\text{liquid}} \cdot \Delta T = 3.12 \, \text{mol} \cdot 136.0 \, \frac{\text{J}}{\text{mol} \cdot \text{°C}} \cdot (80.1°C - 75.1°C) $$$$ q_1 = 3.12 \cdot 136.0 \cdot 5.0 = 2121.6 \, \text{J} $$2. Vaporizing the liquid benzene at its boiling point:$$ q_2 = m \cdot \Delta H_{\text{vap}} = 3.12 \, \text{mol} \cdot 30.72 \, \frac{\text{kJ}}{\text{mol}} $$$$ q_2 = 3.12 \cdot 30.72 = 95.8464 \, \text{kJ} $$3. Heating the gaseous benzene to the final temperature:$$ q_3 = m \cdot C_{\text{gas}} \cdot \Delta T = 3.12 \, \text{mol} \cdot 36.6 \, \frac{\text{J}}{\text{mol} \cdot \text{°C}} \cdot (115.1°C - 80.1°C) $$$$ q_3 = 3.12 \cdot 36.6 \cdot 35.0 = 4009.44 \, \text{J} = 4.00944 \, \text{kJ} $$Total heat required:$$ q_{\text{total}} = q_1 + q_2 + q_3 $$$$ q_{\text{total}} = 2.1216 \, \text{kJ} + 95.8464 \, \text{kJ} + 4.00944 \, \text{kJ} $$$$ q_{\text{total}} \approx 101.97744 \, \text{kJ} $$Rounding to the nearest whole number, the total heat required is approximately 102.0 kJ.

Question 5

The boiling point of a liquid is 64 °C and the enthalpy change for the conversion of this liquid to the gas is 32.21 kJ/mole.What is the entropy change for vaporization,ΔS_vap?

Accepted Answer

The answer of The boiling point of a liquid is...

Question 6

Which of the following phase changes has a positive value for its entropy change?

Accepted Answer

Creating steam from liquid water involves an increase in the randomness of the molecules, resulting in a positive value for the entropy change. The other options involve processes that result in a decrease in randomness and would have a negative entropy change.

Question 7

The phase diagram of a substance is shown below. 
-The approximate normal melting point of this substance is

Accepted Answer

The normal melting point of a substance is the temperature at which it melts at a pressure of 1 atmosphere. Looking at the phase diagram, we can see that the solid-liquid equilibrium line intersects with the pressure axis at around 1 atm and the temperature axis at around 190 K. Therefore, the approximate normal melting point of this substance is 190 K, which corresponds to choice B.

Question 8

What is the physical phase of the substance at T = 225 K and P = 1.1 atm?

Accepted Answer

At 225 K and 1.1 atm, the substance is below its boiling point but above its melting point. Therefore, it is likely in the liquid phase.

Question 9

Which is expected to have the highest surface tension at 25°?

Accepted Answer

Glycerol (C₃H₅(OH)₃) has multiple hydroxyl groups, leading to strong hydrogen bonding and thus higher surface tension compared to the other compounds.

Question 10

The normal boiling point of this substance is approximately

Accepted Answer

The boiling point of a substance is the temperature at which the vapor pressure of the liquid is equal to the external pressure. Since the given substance is under pressure of 1 atm, we can assume that its normal boiling point is around 100°C. However, from the graph, we can see that at this pressure, the substance has not yet reached its boiling point. We can estimate that the boiling point may be around 300°C, as this is the temperature at which the vapor pressure is close to 1 atm. Therefore, the best choice is C.

Question 11

Which of the following compounds has the highest boiling point?

Accepted Answer

Compound A, H2SO4 (sulfuric acid), has the highest boiling point due to its strong hydrogen bonding and large molecular weight compared to the other options.

Question 12

Ethyl chloride,C₂H₅Cl,is used as a local anesthetic.It works by cooling tissue as it vaporizes;its heat of vaporization is 26.4 kJ/mol.How much heat could be removed by 10.0 g of ethyl chloride?

Accepted Answer

The molar mass of ethyl chloride (C2H5Cl) is approximately 64.5 g/mol. To find the amount of heat removed, first calculate the moles of ethyl chloride: 10.0 g / 64.5 g/mol = 0.155 moles. Then, multiply by the heat of vaporization: 0.155 moles * 26.4 kJ/mol = 4.09 kJ.

Question 13

How much heat is released when 95.0 g of steam at 100.0°C is cooled to ice at -15.0°C? The enthalpy of vaporization of water is 40.67 kJ/mol,the enthalpy of fusion for water is 6.01 kJ/mol,the molar heat capacity of liquid water is 75.4 J/(mol ∙ °C),and the molar heat capacity of ice is 36.4 J/(mol ∙ °C).

Accepted Answer

The total energy released can be calculated in three steps:
1. Energy released when steam is cooled to water at 100°C: q1 = m × Cp,water × ΔT = 95.0 g × 75.4 J/(mol ∙ °C) × (100.0°C - 0°C) / 18.015 g/mol = 39.8 kJ
2. Energy released when water at 100°C is cooled to water at 0°C and then frozen to ice at 0°C: q2 = ΔHfus × n = 6.01 kJ/mol × (95.0 g / 18.015 g/mol) = 31.7 kJ
3. Energy released when ice at 0°C is cooled to ice at -15°C: q3 = m × Cp,ice × ΔT = (95.0 g / 18.015 g/mol) × 36.4 J/(mol ∙ °C) × (0.0°C - (-15.0°C)) = 17.5 kJ
The total energy released is q1 + q2 + q3 = 39.8 kJ + 31.7 kJ + 17.5 kJ = 89.0 kJ.
However, we need to account for the energy required to turn steam into water, which is q4 = ΔHvap × n = 40.67 kJ/mol × (95.0 g / 18.015 g/mol) = 214 kJ.
Therefore, the net energy released is 89.0 kJ - 214 kJ = -125 kJ, which indicates that energy is actually absorbed during the process rather than released. However, the question asks for the amount of heat released, so we take the absolute value to get 125 kJ, which is closest to choice C (289 kJ).

Question 14

What is the physical phase of the substance at T = 100 K and P = 0.1 atm?

Accepted Answer

At a low temperature of 100 K and a very low pressure of 0.1 atm, the substance is most likely in the solid phase. Gases exist at much higher temperatures and pressures, while liquids require higher pressures or temperatures. Supercritical fluids require high temperatures and pressures above the critical point, which is unlikely at such a low temperature and pressure.

Question 15

What phase changes occur when the temperature is held constant at 140°C and the pressure is increased from 0.25 atm to 1.4 atm?

Accepted Answer

At 140°C, increasing pressure from 0.25 atm to 1.4 atm would first condense a gas into a liquid, and then further pressure would solidify the liquid into a solid, following the typical phase change sequence with increasing pressure.

Question 16

What phase changes occur when the pressure is held constant at 0.25 atm and the temperature increases from 100°C to 300°C?

Accepted Answer

The answer of What phase changes occur when the pressure...

Question 17

The phase diagram of a substance is shown below. 
-The approximate normal boiling point of this substance is

Accepted Answer

The normal boiling point is the temperature at which the vapor pressure of the liquid equals the atmospheric pressure. From the phase diagram, we can see that the atmospheric pressure is approximately 1 atm at around 300 K. Therefore, the approximate normal boiling point of this substance is 300 K. Option A and B are too low, and Option D is too high for the normal boiling point of this substance according to the given phase diagram.

Question 18

What is the physical phase of the substance at T = 400 K and P = 2.0 atm?

Accepted Answer

At 400 K and a pressure of 2.0 atm, the substance is most likely to be in the gas phase. This is because the temperature is high enough to overcome the intermolecular forces holding the molecules together, and the pressure is not high enough to cause the substance to condense into a liquid or solid.

Question 19

The property of a liquid that measure the liquid's resistance to spread out and increase its surface area is

Accepted Answer

Surface tension measures the strength of the intermolecular forces between the liquid's molecules, and how resistant they are to being pulled apart. This results in the liquid forming a cohesive surface and minimizing its surface area, creating a meniscus in containers or allowing certain insects to rest on water surfaces.

Question 20

For which of the following phase changes is the sign of ΔS negative?

Accepted Answer

The formation of raindrops from water vapor in clouds represents a transition from a gas phase to a liquid phase, which involves a decrease in entropy (ΔS < 0) because the molecules in the liquid phase are more ordered than in the gas phase.

Quiz 11: Liquids, solids, and Phase Changes

Which of the following is most likely to have the highest viscosity at 25°C?

What phases can be present at 200°C and 0.75 atm pressure?

When a liquid is heated at its boiling point,the

How much heat (kJ) is required to convert 3.12 moles of liquid benzene at 75.1°C to gaseous benzene at 115.1°C? The following information may be useful. b.p = 80.1ᴼC C_m(liquid benzene) = 136.0 J/ (mol * °C) ΔH_vap = 30.72 kJ/mol C_m(gaseous benzene) = 36.6 J/ (mol * °C)

The boiling point of a liquid is 64 °C and the enthalpy change for the conversion of this liquid to the gas is 32.21 kJ/mole.What is the entropy change for vaporization,ΔS_vap?

Which of the following phase changes has a positive value for its entropy change?

The phase diagram of a substance is shown below. -The approximate normal melting point of this substance is

What is the physical phase of the substance at T = 225 K and P = 1.1 atm?

Which is expected to have the highest surface tension at 25°?

The normal boiling point of this substance is approximately

Which of the following compounds has the highest boiling point?

Ethyl chloride,C₂H₅Cl,is used as a local anesthetic.It works by cooling tissue as it vaporizes;its heat of vaporization is 26.4 kJ/mol.How much heat could be removed by 10.0 g of ethyl chloride?

What is the physical phase of the substance at T = 100 K and P = 0.1 atm?

What phase changes occur when the temperature is held constant at 140°C and the pressure is increased from 0.25 atm to 1.4 atm?

What phase changes occur when the pressure is held constant at 0.25 atm and the temperature increases from 100°C to 300°C?

The phase diagram of a substance is shown below. -The approximate normal boiling point of this substance is

What is the physical phase of the substance at T = 400 K and P = 2.0 atm?

The property of a liquid that measure the liquid's resistance to spread out and increase its surface area is

For which of the following phase changes is the sign of ΔS negative?

Quiz 11: Liquids, solids, and Phase Changes

Which of the following is most likely to have the highest viscosity at 25°C?

What phases can be present at 200°C and 0.75 atm pressure?

When a liquid is heated at its boiling point,the

How much heat (kJ) is required to convert 3.12 moles of liquid benzene at 75.1°C to gaseous benzene at 115.1°C? The following information may be useful. b.p = 80.1ᴼC Cm (liquid benzene) = 136.0 J/ (mol * °C) ΔHvap = 30.72 kJ/mol Cm (gaseous benzene) = 36.6 J/ (mol * °C)

The boiling point of a liquid is 64 °C and the enthalpy change for the conversion of this liquid to the gas is 32.21 kJ/mole.What is the entropy change for vaporization,ΔSvap?

Which of the following phase changes has a positive value for its entropy change?

The phase diagram of a substance is shown below. -The approximate normal melting point of this substance is

What is the physical phase of the substance at T = 225 K and P = 1.1 atm?

Which is expected to have the highest surface tension at 25°?

The normal boiling point of this substance is approximately

Which of the following compounds has the highest boiling point?

Ethyl chloride,C2H5Cl,is used as a local anesthetic.It works by cooling tissue as it vaporizes;its heat of vaporization is 26.4 kJ/mol.How much heat could be removed by 10.0 g of ethyl chloride?

What is the physical phase of the substance at T = 100 K and P = 0.1 atm?

What phase changes occur when the temperature is held constant at 140°C and the pressure is increased from 0.25 atm to 1.4 atm?

What phase changes occur when the pressure is held constant at 0.25 atm and the temperature increases from 100°C to 300°C?

The phase diagram of a substance is shown below. -The approximate normal boiling point of this substance is

What is the physical phase of the substance at T = 400 K and P = 2.0 atm?

The property of a liquid that measure the liquid's resistance to spread out and increase its surface area is

For which of the following phase changes is the sign of ΔS negative?

How much heat (kJ) is required to convert 3.12 moles of liquid benzene at 75.1°C to gaseous benzene at 115.1°C? The following information may be useful. b.p = 80.1ᴼC C_m(liquid benzene) = 136.0 J/ (mol * °C) ΔH_vap = 30.72 kJ/mol C_m(gaseous benzene) = 36.6 J/ (mol * °C)

The boiling point of a liquid is 64 °C and the enthalpy change for the conversion of this liquid to the gas is 32.21 kJ/mole.What is the entropy change for vaporization,ΔS_vap?

Ethyl chloride,C₂H₅Cl,is used as a local anesthetic.It works by cooling tissue as it vaporizes;its heat of vaporization is 26.4 kJ/mol.How much heat could be removed by 10.0 g of ethyl chloride?