Question 1

Chlorine, Cl₂, is a gas at room temperature, but bromine, Br₂, is a liquid. Explain.

Accepted Answer

Bromine atoms are larger than chlorine atoms, which increases the strength of London dispersion forces between molecules. The stronger intermolecular forces in bromine result in a higher boiling point and liquid state at room temperature.

Question 2

The charges with sodium chloride are all balanced-for every positive sodium ion there is a corresponding negative chloride ion. Since its charges are balanced, how can sodium chloride be attracted to water, and vice versa?

Accepted Answer

As a water molecule gets close to the sodium chloride, it can distinguish the various ions and is attracted to individual ions by ion-dipole forces. These forces are stronger than the attractive forces between the ions in the crystal lattice of sodium chloride, causing the ions to separate and become surrounded by water molecules. This process of dissolution is known as hydration or solvation.

Question 3

Which of the following intermolecular forces best describes why molecules like CF3CF3 are soluble in liquid CO₂?

Accepted Answer

CF3CF3 and CO2 are both nonpolar molecules, so the primary intermolecular force between them is induced dipole-induced dipole (also known as London dispersion forces). These forces are present in all molecular interactions but are the only type for nonpolar molecules.

Question 4

Each circle represents an atom. Which of the following boxes contains an element? A compound? A mixture?

Accepted Answer

The answer of Each circle represents an atom. Which of...

Question 5

Two chemical structures are shown, one of a typical gasoline molecule and the other of a typical motor oil molecule. Which is which?  Base your reasoning not on memorization but rather upon what you know about molecular interactions and the various physical properties of gasoline and motor oil.

Accepted Answer

The answer of Two chemical structures are shown, one of...

Question 6

What is the difference between a compound and a mixture?

Accepted Answer

A compound is made up of two or more different elements that are chemically combined and cannot be physically separated into their individual components. A mixture, on the other hand, is made up of two or more substances that are physically combined and can be separated into their individual components by physical means such as filtration or distillation.

Question 7

Which of the following is a mixture?

Accepted Answer

Air is a mixture of various gases such as oxygen, nitrogen, carbon dioxide, and others.

Question 8

The following image represents which kind of matter?

Accepted Answer

The answer of The following image represents which kind of...

Question 9

Plastic wrap is made of nonpolar molecules and is able to stick well to polar surfaces, such as glass, by way of dipole/induced dipole molecular attractions. How is it that plastic wrap also sticks to itself so well?

Accepted Answer

Plastic wrap sticks to itself by way of induced dipole-induced dipole molecular attractions, also known as London dispersion forces. Even though the plastic wrap is made of nonpolar molecules, electron imbalance can create temporary dipoles, leading to weak attractions between molecules. When the plastic wrap is pressed against itself, these weak attractions cause the wrap to stick together.

Question 10

Why is calcium fluoride, CaF2, a high melting point crystalline solid while stannic chloride, SnCl₄, is a volatile liquid?

Accepted Answer

Calcium fluoride (CaF2) is an ionic compound, which generally have high melting points due to the strong electrostatic attraction between ions. Stannic chloride (SnCl4) is more covalently bonded, making it less rigid and easier to become a volatile liquid.

Question 11

The following image represents which kind of matter?

Accepted Answer

The answer of The following image represents which kind of...

Question 12

Why are ion-dipole attractions stronger than dipole-dipole attractions?

Accepted Answer

Ion-dipole attractions are stronger than dipole-dipole attractions because the magnitude of the electric charge associated with an ion is much greater than the magnitude of the partial charges associated with a dipole. This results in a stronger attraction between the ion and the dipole than between two dipoles.

Question 13

List the following compounds in order of increasing boiling point: Cl₄, CBr₄, CCl₄, CF₄.

Accepted Answer

Boiling points of halogenated compounds generally increase with the size and molecular weight of the halogen atom due to increased van der Waals forces. Therefore, the order from lowest to highest boiling point, considering fluorine (F) is the smallest and lightest and iodine (I) is the largest and heaviest, is CF4, CCl4, CBr4, and CI4.

Question 14

How are oxygen molecules attracted to water molecules?

Accepted Answer

The answer of How are oxygen molecules attracted to water...

Question 15

Consider the boiling points of the following compounds and their solubilities in room-temperature water. Why does the solubilities in water go down as the boiling points of these alcohols go up.

Accepted Answer

The answer of Consider the boiling points of the following...

Question 16

Dipole-induced dipole forces of attraction exist between water and gasoline, and yet these two substances do not mix because water has such a strong attraction for itself. Which of the following compounds might best help to make these two substances mix into a single liquid phase?

Accepted Answer

The answer of Dipole-induced dipole forces of attraction exist between...

Question 17

Why is the surface area of a gecko's foot so extensive?

Accepted Answer

The extensive surface area of a gecko's foot allows for a greater number of induced dipole-induced dipole forces of attraction that can occur between the gecko's foot and the surface it is climbing on, which helps the gecko to maintain grip and climb even on smooth surfaces.

Question 18

A combination of two or more substances in which they no longer retain their chemical properties is called a(n)

Accepted Answer

A compound is formed when two or more substances chemically combine, resulting in a substance that has different properties from the original substances.

Question 19

Why are the melting temperatures of most ionic compounds far greater than the melting temperatures of most covalent compounds?

Accepted Answer

The answer of Why are the melting temperatures of most...

Question 20

The boiling point of 1,4-butanediol is 230°C. Would you expect this compound to be soluble or insoluble in room-temperature water?

Accepted Answer

The answer of The boiling point of 1,4-butanediol is 230°C....

Quiz 12: Chemical Bonds and Mixtures

Chlorine, Cl2, is a gas at room temperature, but bromine, Br2, is a liquid. Explain.

The charges with sodium chloride are all balanced-for every positive sodium ion there is a corresponding negative chloride ion. Since its charges are balanced, how can sodium chloride be attracted to water, and vice versa?

Which of the following intermolecular forces best describes why molecules like CF3CF3 are soluble in liquid CO₂?

Each circle represents an atom. Which of the following boxes contains an element? A compound? A mixture?

Two chemical structures are shown, one of a typical gasoline molecule and the other of a typical motor oil molecule. Which is which? Base your reasoning not on memorization but rather upon what you know about molecular interactions and the various physical properties of gasoline and motor oil.

What is the difference between a compound and a mixture?

Which of the following is a mixture?

The following image represents which kind of matter?

Plastic wrap is made of nonpolar molecules and is able to stick well to polar surfaces, such as glass, by way of dipole/induced dipole molecular attractions. How is it that plastic wrap also sticks to itself so well?

Why is calcium fluoride, CaF2, a high melting point crystalline solid while stannic chloride, SnCl4, is a volatile liquid?

The following image represents which kind of matter?

Why are ion-dipole attractions stronger than dipole-dipole attractions?

List the following compounds in order of increasing boiling point: Cl4, CBr4, CCl4, CF4.

How are oxygen molecules attracted to water molecules?

Consider the boiling points of the following compounds and their solubilities in room-temperature water. Why does the solubilities in water go down as the boiling points of these alcohols go up.

Dipole-induced dipole forces of attraction exist between water and gasoline, and yet these two substances do not mix because water has such a strong attraction for itself. Which of the following compounds might best help to make these two substances mix into a single liquid phase?

Why is the surface area of a gecko's foot so extensive?

A combination of two or more substances in which they no longer retain their chemical properties is called a(n)

Why are the melting temperatures of most ionic compounds far greater than the melting temperatures of most covalent compounds?

The boiling point of 1,4-butanediol is 230°C. Would you expect this compound to be soluble or insoluble in room-temperature water?

Chlorine, Cl₂, is a gas at room temperature, but bromine, Br₂, is a liquid. Explain.

Why is calcium fluoride, CaF2, a high melting point crystalline solid while stannic chloride, SnCl₄, is a volatile liquid?

List the following compounds in order of increasing boiling point: Cl₄, CBr₄, CCl₄, CF₄.