Question 1

Which of the following forms a molecular solid?

Accepted Answer

The answer of Which of the following forms a molecular...

Question 2

Which is expected to have the largest dispersion forces?

Accepted Answer

The molecule with the highest number of electrons will have the largest dispersion forces. In this case, option B has the highest number of atoms and therefore the highest number of electrons, making it likely to have the largest dispersion forces.

Question 3

Which has the smallest dipole-dipole forces?

Accepted Answer

The answer of Which has the smallest dipole-dipole forces?
...

Question 4

Which type of bonding does Sr form upon solidification?

Accepted Answer

The answer of Which type of bonding does Sr form...

Question 5

Which of the following molecules does not have a dipole moment?

Accepted Answer

Molecules with a dipole moment have a separation of charges, resulting in a positive and negative end. In molecule A, the symmetric arrangement of the atoms cancels out the dipole moments, resulting in no overall dipole moment. Molecules B and C have a dipole moment due to the electronegativity difference between the atoms. Molecule D is a diatomic molecule and does not have a dipole moment.

Question 6

A certain metal crystallizes in a face-centered cubic structure.What is the edge length of the unit cell if the atomic radius of the metal is 144 pm?

Accepted Answer

In a face-centered cubic (FCC) structure, the edge length (a) is related to the atomic radius (r) by the formula a = 2√2r. Substituting r = 144 pm, we get a = 2√2 * 144 pm ≈ 407 pm.

Question 7

What is the edge length of a face-centered cubic unit cell made up of atoms having a radius of 128 pm?

Accepted Answer

In a face-centered cubic (FCC) unit cell, the edge length (a) is related to the atomic radius (r) by the formula a = 2√2r. Substituting r = 128 pm, we get a = 2√2 * 128 pm = 362 pm.

Question 8

Na Cl crystallizes in a cubic unit cell with Cl^- ions on each corner and each face.How many Na⁺ and Cl^- ions are in each unit cell of Na Cl?

Accepted Answer

In a cubic unit cell, the corner atoms contribute 1/8th of an atom each to the unit cell, and there are 8 corners, so the total contribution from corners is 1 atom. The face-centered atoms contribute 1/2 an atom each, and there are 6 faces, so the total contribution from faces is 3 atoms. Since Cl^- ions are on each corner and each face, they contribute a total of 4 Cl^- ions per unit cell. Na^+ ions occupy the octahedral voids in the structure, matching the number of Cl^- ions to maintain charge neutrality, resulting in 4 Na^+ ions per unit cell.

Question 9

Lithium crystallizes in a body-centered cubic structure.What is the coordination number of each atom?

Accepted Answer

In a body-centered cubic structure, each atom has eight nearest neighbors located at the corners of the cube and an additional atom at the center of the cube. So, the coordination number of each Lithium atom is 8.

Question 10

Nickel has a face-centered cubic structure and has a density of 8.90 g/cm³.What is its atomic radius?

Accepted Answer

The density of a face-centered cubic structure is given by:$$ho = \frac{4AM}{a^3N_A}$$where $ho$ is the density, $A$ is the atomic weight, $M$ is the molar mass, $a$ is the edge length of the unit cell, $N_A$ is Avogadro's number.We can rearrange this equation to solve for the atomic radius:$$r = \frac{a\sqrt{2}}{4}$$Substituting the given values into this equation, we get:$$r = \frac{(3.52 	imes 10^{-8} 	ext{ cm})\sqrt{2}}{4} = 2.49 	imes 10^{-8} 	ext{ cm} = 249 	ext{ pm}$$Therefore, the atomic radius of nickel is 249 pm.

Question 11

Cesium has a radius of 272 pm and crystallizes in a body-centered cubic structure.What is the edge length of the unit cell?

Accepted Answer

In a body-centered cubic (BCC) structure, the relationship between the atomic radius (r) and the edge length (a) is given by: a = 4r/√3. For cesium, with r = 272 pm, the edge length a = 4(272 pm)/√3 ≈ 628 pm.

Question 12

How much heat is released when 105 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

First, we need to calculate the amount of heat released when steam at 100.0°C is cooled to liquid water at 100.0°C using the equation:

q1 = m × C × ΔT

where q1 is the amount of heat released, m is the mass of steam, C is the molar heat capacity of liquid water, and ΔT is the temperature change.

Here, we have:

m = 105 g/ 18.015 g/mol = 5.829 mol (mass/molecular weight)
C = 75.4 J/(mol ∙ °C)
ΔT = 100.0°C - 0°C = 100.0°C

q1 = 5.829 mol × 75.4 J/(mol ∙ °C) × 100.0°C = 43,802 J

Next, we need to calculate the amount of heat released when the liquid water at 100.0°C is cooled to ice at 0.0°C using the equation:

q2 = m × C × ΔT

where q2 is the amount of heat released, m is the mass of liquid water, C is the molar heat capacity of ice, and ΔT is the temperature change.

Here, we have:

m = 5.829 mol
C = 36.4 J/(mol ∙ °C)
ΔT = 0.0°C - (-100.0°C) = 100.0°C

q2 = 5.829 mol × 36.4 J/(mol ∙ °C) × 100.0°C = 21,223 J

Finally, we need to calculate the amount of heat released when the ice at 0.0°C is cooled to ice at -15.0°C using the equation:

q3 = m × ΔHfus + m × C × ΔT

where q3 is the amount of heat released, m is the mass of ice, ΔHfus is the enthalpy of fusion for water, C is the molar heat capacity of ice, and ΔT is the temperature change.

Here, we have:

m = 5.829 mol
ΔHfus = 6.01 kJ/mol
C = 36.4 J/(mol ∙ °C)
ΔT = -15.0°C - 0.0°C = -15.0°C

q3 = 5.829 mol × 6.01 kJ/mol + 5.829 mol × 36.4 J/(mol ∙ °C) × (-15.0°C) = -17,223 J

The total amount of heat released is the sum of q1, q2, and q3:

q = q1 + q2 + q3 = 43,802 J + 21,223 J - 17,223 J = 47,802 J

Finally, we need to convert J to kJ:

q = 47,802 J = 47.802 kJ

Hence, the best choice is C (319 kJ) since it is the closest answer to our calculated value.

Question 13

Which of the following compounds exhibits only dispersion and dipole-dipole intermolecular interactions?

Accepted Answer

Only compounds with polar molecules can exhibit dipole-dipole interactions. Among the given compounds, only HI has polar covalent bonds (due to electronegativity difference between H and I), therefore it can have both dispersion and dipole-dipole interactions. The other compounds do not have polar bonds, and hence can exhibit only dispersion forces.

Question 14

In liquid propanol,CH₃CH₂CH₂OH,which intermolecular forces are present?

Accepted Answer

The molecule of liquid propanol contains polar covalent bonds due to the electronegativity difference between oxygen and hydrogen atoms. This results in a dipole moment in the molecule. Therefore, dipole-dipole forces are present. Additionally, the molecule contains an -OH functional group that can participate in hydrogen bonding with adjacent molecules. Finally, since propanol is a larger molecule, London dispersion forces are also present between the molecules. Therefore, all three types of intermolecular forces, including dispersion, hydrogen bonding, and dipole-dipole forces, are present in liquid propanol.

Question 15

Which of the following compounds exhibits hydrogen bonding?

Accepted Answer

Ammonia (NH3) exhibits hydrogen bonding due to the presence of a nitrogen atom bonded to hydrogen, which creates a significant dipole and allows for hydrogen bonds to form between molecules.

Question 16

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 20.0 g of ethyl chloride?

Accepted Answer

The molar mass of ethyl chloride (C2H5Cl) is approximately 64.5 g/mol. Therefore, 20.0 g corresponds to about 0.31 mol. The heat removed is calculated by multiplying the moles by the heat of vaporization: 0.31 mol * 26.4 kJ/mol = 8.18 kJ.

Question 17

The normal boiling point for H₂Te is higher than the normal boiling point for H₂Se.This can be explained by

Accepted Answer

H₂Te has larger dispersion forces due to its larger molar mass compared to H₂Se, leading to a higher boiling point.

Question 18

Which of the following forms an ionic solid?

Accepted Answer

RbI1 forms an ionic solid because it is a combination of a metal (Rb) and a non-metal (I). Ag is a metal and forms a metallic solid, C₇H₁₅NH₂ is a molecular solid, and SO₃ is a covalent solid.

Question 19

Which of the following compounds has the highest boiling point?

Accepted Answer

Water (H2O) has the highest boiling point due to strong hydrogen bonding between its molecules, which requires more energy to break compared to the other compounds listed.

Question 20

Which of the following should have the largest dipole moment?

Accepted Answer

The answer of Which of the following should have the...

Quiz 10: Liquids,solids,and Phase Changes

Which of the following forms a molecular solid?

Which is expected to have the largest dispersion forces?

Which has the smallest dipole-dipole forces?

Which type of bonding does Sr form upon solidification?

Which of the following molecules does not have a dipole moment?

A certain metal crystallizes in a face-centered cubic structure.What is the edge length of the unit cell if the atomic radius of the metal is 144 pm?

What is the edge length of a face-centered cubic unit cell made up of atoms having a radius of 128 pm?

Na Cl crystallizes in a cubic unit cell with Cl- ions on each corner and each face.How many Na+ and Cl- ions are in each unit cell of Na Cl?

Lithium crystallizes in a body-centered cubic structure.What is the coordination number of each atom?

Nickel has a face-centered cubic structure and has a density of 8.90 g/cm3.What is its atomic radius?

Cesium has a radius of 272 pm and crystallizes in a body-centered cubic structure.What is the edge length of the unit cell?

Which of the following compounds exhibits only dispersion and dipole-dipole intermolecular interactions?

In liquid propanol,CH3CH2CH2OH, which intermolecular forces are present?

Which of the following compounds exhibits hydrogen bonding?

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 20.0 g of ethyl chloride?

The normal boiling point for H2Te is higher than the normal boiling point for H2Se .This can be explained by

Which of the following forms an ionic solid?

Which of the following compounds has the highest boiling point?

Which of the following should have the largest dipole moment?

Na Cl crystallizes in a cubic unit cell with Cl^- ions on each corner and each face.How many Na⁺ and Cl^- ions are in each unit cell of Na Cl?

Nickel has a face-centered cubic structure and has a density of 8.90 g/cm³.What is its atomic radius?

In liquid propanol,CH₃CH₂CH₂OH,which intermolecular forces are present?

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 20.0 g of ethyl chloride?

The normal boiling point for H₂Te is higher than the normal boiling point for H₂Se.This can be explained by