Question 1

The enthalpy change for converting 1.00 mol of ice at -25.0 °C to water at 50.0 °C is ________ kJ. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H₂O, ΔH_fus = 6.01 kJ/mol, and ΔH_vap = 40.67 kJ/mol.

Accepted Answer

The enthalpy change for this process can be calculated in two steps:
1. Calculate the heat required to raise the temperature of ice from -25°C to 0°C and then to melt the ice at 0°C:
q1 = [(-25°C to 0°C) * 2.09 J/g-K * 1.00 mol] + [1.00 mol * 6.01 kJ/mol] = -54.83 kJ
2. Calculate the heat required to raise the temperature of the water from 0°C to 50°C:
q2 = [(50°C-0°C) * 4.18 J/g-K * 1.00 mol] = 209 kJ
Therefore, the total enthalpy change is:
ΔH = q1 + q2 = 154.17 kJ
Rounding to two decimal places, the answer is 10.71 kJ.

Question 2

London Dispersion Forces tend to ________ in strength with increasing molecular weight.

Accepted Answer

The answer of London Dispersion Forces tend to ________ in...

Question 3

What is the predominant intermolecular force in H₂NNH₂?

Accepted Answer

The chemical formula H₂NNH₂ seems to be incorrectly formatted or a typographical error. However, assuming it involves hydrogen (H), sulfur (S), boron (B), and nitrogen (N), hydrogen bonding is the most plausible predominant intermolecular force. Hydrogen bonding occurs when hydrogen is bonded to highly electronegative atoms like nitrogen, oxygen, or fluorine, which seems applicable here given the presence of hydrogen and nitrogen.

Question 4

The initial discovery of a liquid crystal resulted from studies on what compound?

Accepted Answer

The answer of The initial discovery of a liquid crystal...

Question 5

Of the following, ________ is the most volatile.

Accepted Answer

The presence of chlorine (Cl) makes the compound more volatile as it has a lower boiling point compared to the other options. Therefore, option D (C₂Cl₆) is the most volatile.

Question 6

Boron triiodide (BI₃)melts at 49.9 °C and boils at 209.5 °C at a constant pressure of 1 atm. What state of matter must a sample of boron triiodide be in at 100°C and 1 atm?

Accepted Answer

At 100°C and 1 atm, boron triiodide is below its boiling point of 209.5 °C but above its melting point of 49.9°C. This means that it is in a temperature range where it can exist in either solid or liquid form. However, since the question asks for the most likely state of matter, we can eliminate choices B, D, and E since they represent states that would not be as likely as either solid or liquid at this temperature and pressure. Therefore, the best choice would be A) liquid, as boron triiodide would more likely be in liquid form at this temperature and pressure.

Question 7

Ethanol (C₂H₅OH)melts at -114 °C. The enthalpy of fusion is 5.02 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/g-K and 2.3 J/g-K, respectively. How much heat (kJ)is needed to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -60 °C?

Accepted Answer

The answer of Ethanol (C₂H₅OH)melts at -114 °C. The enthalpy...

Question 8

What is the predominant intermolecular force in HCN?

Accepted Answer

HCN has a polar covalent bond due to the electronegativity difference between Hydrogen and Carbon, therefore, there is a permanent dipole moment. The strongest intermolecular force available for HCN is dipole-dipole attraction.

Question 9

The enthalpy change for converting 10.0 g of ice at -50.0 °C to water at 50.0 °C is ________ kJ. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H₂O, ΔH_fus = 6.01 kJ/mol, and ΔH_vap = 40.67 kJ/mol.

Accepted Answer

The answer of The enthalpy change for converting 10.0 g...

Question 10

-The phase diagram of a substance is given above. This substance is a ________ at 30 °C and 0.5 atm.

Accepted Answer

The answer of 
-The phase diagram of a substance is...

Question 11

In general, intramolecular forces determine the ________ properties of a substance and intermolecular forces determine its ________ properties.

Accepted Answer

The answer of In general, intramolecular forces determine the ________...

Question 12

Ethanol melts at -114 °C and boils at 78 °C at a constant pressure of 1 atm. What state of matter must a sample of ethanol be in at 0°C and 1 atm?

Accepted Answer

At 0°C and 1 atm pressure, ethanol would be in a state where it is colder than its boiling point but warmer than its melting point. Therefore, it would be in a liquid state.

Question 13

Calculate the enthalpy change (in kJ)associated with the conversion of 25.0 grams of ice at -4.00 °C to water vapor at 109.0 °C. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H₂O, ΔH_fus = 6.01 kJ/mol and ΔH_vap = 40.67 kJ/mol.

Accepted Answer

The process of converting ice to water vapor involves several steps and each step contributes to the total enthalpy change. We can break down the process into the following steps:

1. Heating the ice from -4.00 °C to 0.00 °C and melting it to water at 0.00 °C.
2. Heating the water from 0.00 °C to 100.00 °C and vaporizing it to steam at 100.00 °C.
3. Heating the steam from 100.00 °C to 109.00 °C.

To calculate the enthalpy change for each step, we need to use the following formulas:

q = mCΔT (for heating or cooling)
q = nΔH (for melting or vaporization)

where q is the heat absorbed or released, m is the mass of the substance, C is the specific heat of the substance, ΔT is the change in temperature, n is the moles of the substance, and ΔH is the enthalpy of melting or vaporization.

Step 1: Heating and melting the ice

q = (25.0 g)(2.09 J/g-K)(0.00 °C - (-4.00 °C)) = 209 J (heating)
q = (25.0 g)/(18.015 g/mol)(6.01 kJ/mol) = 20.8 kJ (melting)

Step 2: Heating and vaporizing the water

q = (25.0 g)(4.18 J/g-K)(100.00 °C - 0.00 °C) = 10,450 J (heating)
q = (25.0 g)/(18.015 g/mol)(40.67 kJ/mol) = 58.1 kJ (vaporization)

Step 3: Heating the steam

q = (25.0 g)(1.84 J/g-K)(109.00 °C - 100.00 °C) = 407 J (heating)

The total enthalpy change is the sum of the enthalpy changes for each step:

ΔH = 20.8 kJ + 58.1 kJ + 407 J = 79.3 kJ

The answer is closest to choice B: 75.9 kJ. However, this is not an option, so the best choice is B. The answer is positive because energy is absorbed by the system (ice) to overcome the intermolecular forces and change its state to water vapor.

Question 14

The heat of fusion of water is 6.01 kJ/mol. The heat capacity of liquid water is 75.3 J/mol ∙ K. The conversion of 50.0 g of ice at 0.00 °C to liquid water at 0.00°C requires ________ kJ of heat.

Accepted Answer

To calculate the heat required to convert 50.0 g of ice to liquid water, we need to use the following formula:

q = m × ΔHfus

where

q = heat required (in kJ) 
m = mass of substance (in g) 
ΔHfus = heat of fusion (in kJ/mol)

First, we need to determine the number of moles of water that are present in 50.0 g of ice:

n = m ÷ M

where

n = number of moles 
m = mass (in g) 
M = molar mass (in g/mol)

The molar mass of water is 18.02 g/mol, so:

n = 50.0 g ÷ 18.02 g/mol = 2.78 mol

Now, we can use the formula to calculate the heat required:

q = 2.78 mol × 6.01 kJ/mol = 16.7 kJ

Therefore, the answer is B (16.7).

Question 15

-Based on the figure above, the boiling point of water under an external pressure of 0.211 atm is ________ °C.

Accepted Answer

At an external pressure of 0.211 atm, the boiling point of water is approximately 60°C.

Question 16

The principal source of the difference in the normal boiling points of ICl (97 °C; molecular mass 162 amu)and Br₂ (59 °C; molecular mass 160 amu)is both dipole-dipole interactions and London dispersion forces.

Accepted Answer

The answer of The principal source of the difference in...

Question 17

Of the following, ________ is the least volatile.

Accepted Answer

The answer of Of the following, ________ is the least...

Question 18

The direct conversion of a solid to a gas is called ________.

Accepted Answer

The answer of The direct conversion of a solid to...

Question 19

-Based on the figure above, the boiling point of ethyl alcohol under an external pressure of 0.658 atm is ________ °C.

Accepted Answer

The boiling point of a liquid decreases as the external pressure decreases. Therefore, the boiling point of ethyl alcohol under an external pressure of 0.658 atm is lower than its boiling point at 1 atm. The boiling point of ethyl alcohol at 1 atm is 78.3 °C. Therefore, the boiling point of ethyl alcohol under an external pressure of 0.658 atm is approximately 70 °C.

Question 20

-Based on the figure above, the boiling point of diethyl ether under an external pressure of 0.605 atm is ________ °C.

Accepted Answer

The answer of 
-Based on the figure above, the boiling...

Quiz 11: Liquids and Intermolecular Forces

The enthalpy change for converting 1.00 mol of ice at -25.0 °C to water at 50.0 °C is ________ kJ. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H₂O, ΔH_fus = 6.01 kJ/mol, and ΔH_vap = 40.67 kJ/mol.

London Dispersion Forces tend to ________ in strength with increasing molecular weight.

What is the predominant intermolecular force in H₂NNH₂?

The initial discovery of a liquid crystal resulted from studies on what compound?

Of the following, ________ is the most volatile.

Boron triiodide (BI₃) melts at 49.9 °C and boils at 209.5 °C at a constant pressure of 1 atm. What state of matter must a sample of boron triiodide be in at 100°C and 1 atm?

Ethanol (C₂H₅OH) melts at -114 °C. The enthalpy of fusion is 5.02 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/g-K and 2.3 J/g-K, respectively. How much heat (kJ) is needed to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -60 °C?

What is the predominant intermolecular force in HCN?

The enthalpy change for converting 10.0 g of ice at -50.0 °C to water at 50.0 °C is ________ kJ. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H₂O, ΔH_fus = 6.01 kJ/mol, and ΔH_vap = 40.67 kJ/mol.

-The phase diagram of a substance is given above. This substance is a ________ at 30 °C and 0.5 atm.

In general, intramolecular forces determine the properties of a substance and intermolecular forces determine its properties.

Ethanol melts at -114 °C and boils at 78 °C at a constant pressure of 1 atm. What state of matter must a sample of ethanol be in at 0°C and 1 atm?

Calculate the enthalpy change (in kJ) associated with the conversion of 25.0 grams of ice at -4.00 °C to water vapor at 109.0 °C. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H₂O, ΔH_fus = 6.01 kJ/mol and ΔH_vap = 40.67 kJ/mol.

The heat of fusion of water is 6.01 kJ/mol. The heat capacity of liquid water is 75.3 J/mol ∙ K. The conversion of 50.0 g of ice at 0.00 °C to liquid water at 0.00°C requires ________ kJ of heat.

-Based on the figure above, the boiling point of water under an external pressure of 0.211 atm is ________ °C.

The principal source of the difference in the normal boiling points of ICl (97 °C; molecular mass 162 amu)and Br₂ (59 °C; molecular mass 160 amu)is both dipole-dipole interactions and London dispersion forces.

Of the following, ________ is the least volatile.

The direct conversion of a solid to a gas is called ________.

-Based on the figure above, the boiling point of ethyl alcohol under an external pressure of 0.658 atm is ________ °C.

-Based on the figure above, the boiling point of diethyl ether under an external pressure of 0.605 atm is ________ °C.

Quiz 11: Liquids and Intermolecular Forces

The enthalpy change for converting 1.00 mol of ice at -25.0 °C to water at 50.0 °C is ________ kJ. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H2O, ΔHfus = 6.01 kJ/mol, and ΔHvap = 40.67 kJ/mol.

London Dispersion Forces tend to ________ in strength with increasing molecular weight.

What is the predominant intermolecular force in H2NNH2?

The initial discovery of a liquid crystal resulted from studies on what compound?

Of the following, ________ is the most volatile.

Boron triiodide (BI3) melts at 49.9 °C and boils at 209.5 °C at a constant pressure of 1 atm. What state of matter must a sample of boron triiodide be in at 100°C and 1 atm?

Ethanol (C2H5OH) melts at -114 °C. The enthalpy of fusion is 5.02 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/g-K and 2.3 J/g-K, respectively. How much heat (kJ) is needed to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -60 °C?

What is the predominant intermolecular force in HCN?

The enthalpy change for converting 10.0 g of ice at -50.0 °C to water at 50.0 °C is ________ kJ. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H2O, ΔHfus = 6.01 kJ/mol, and ΔHvap = 40.67 kJ/mol.

-The phase diagram of a substance is given above. This substance is a ________ at 30 °C and 0.5 atm.

In general, intramolecular forces determine the ________ properties of a substance and intermolecular forces determine its ________ properties.

Ethanol melts at -114 °C and boils at 78 °C at a constant pressure of 1 atm. What state of matter must a sample of ethanol be in at 0°C and 1 atm?

Calculate the enthalpy change (in kJ) associated with the conversion of 25.0 grams of ice at -4.00 °C to water vapor at 109.0 °C. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H2O, ΔHfus = 6.01 kJ/mol and ΔHvap = 40.67 kJ/mol.

The heat of fusion of water is 6.01 kJ/mol. The heat capacity of liquid water is 75.3 J/mol ∙ K. The conversion of 50.0 g of ice at 0.00 °C to liquid water at 0.00°C requires ________ kJ of heat.

-Based on the figure above, the boiling point of water under an external pressure of 0.211 atm is ________ °C.

The principal source of the difference in the normal boiling points of ICl (97 °C; molecular mass 162 amu)and Br2 (59 °C; molecular mass 160 amu)is both dipole-dipole interactions and London dispersion forces.

Of the following, ________ is the least volatile.

The direct conversion of a solid to a gas is called ________.

-Based on the figure above, the boiling point of ethyl alcohol under an external pressure of 0.658 atm is ________ °C.

-Based on the figure above, the boiling point of diethyl ether under an external pressure of 0.605 atm is ________ °C.

The enthalpy change for converting 1.00 mol of ice at -25.0 °C to water at 50.0 °C is ________ kJ. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H₂O, ΔH_fus = 6.01 kJ/mol, and ΔH_vap = 40.67 kJ/mol.

What is the predominant intermolecular force in H₂NNH₂?

Boron triiodide (BI₃) melts at 49.9 °C and boils at 209.5 °C at a constant pressure of 1 atm. What state of matter must a sample of boron triiodide be in at 100°C and 1 atm?

Ethanol (C₂H₅OH) melts at -114 °C. The enthalpy of fusion is 5.02 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/g-K and 2.3 J/g-K, respectively. How much heat (kJ) is needed to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -60 °C?

The enthalpy change for converting 10.0 g of ice at -50.0 °C to water at 50.0 °C is ________ kJ. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H₂O, ΔH_fus = 6.01 kJ/mol, and ΔH_vap = 40.67 kJ/mol.

In general, intramolecular forces determine the properties of a substance and intermolecular forces determine its properties.

Calculate the enthalpy change (in kJ) associated with the conversion of 25.0 grams of ice at -4.00 °C to water vapor at 109.0 °C. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H₂O, ΔH_fus = 6.01 kJ/mol and ΔH_vap = 40.67 kJ/mol.

The principal source of the difference in the normal boiling points of ICl (97 °C; molecular mass 162 amu)and Br₂ (59 °C; molecular mass 160 amu)is both dipole-dipole interactions and London dispersion forces.