Question 1

If the pressure of a gas rises,the gas molecules will strike the walls of its container more frequently. (Assume that the container has a definite shape and volume.)

Accepted Answer

The pressure of a gas is directly proportional to the frequency of gas molecule collisions with the walls of a container. Therefore, if pressure increases, the frequency of collisions will also increase.

Question 2

According to the kinetic-molecular theory,there is very little attraction between particles of a gas.

Accepted Answer

The kinetic-molecular theory of gases assumes that gas particles are in constant random motion and that there are no intermolecular attractions between them. Therefore, option A is true.

Question 3

Use the ideal gas law to calculate the volume occupied by 0.400 mol of nitrogen gas at 3.00 atm pressure and at 27°C.R = 0.0821 L * atm/(K*mol).

Accepted Answer

The ideal gas law is PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature. We can rearrange this equation to solve for V: V = nRT/P. Plugging in the given values, we get V = (0.400 mol)(0.0821 L * atm/(K*mol))(27°C + 273.15 K)/3.00 atm = 17.7 L.

Question 4

If the temperature of a gas is lowered,the gas molecules will strike the walls of its container more frequently. (Assume that the container has a definite shape and volume.)

Accepted Answer

When the temperature of a gas is lowered, the gas molecules lose energy and move slower, causing them to strike the walls of the container less frequently.

Question 5

Assume that you have a sample of a gas.You know the volume,the temperature and the number of moles of the sample.Which of the following laws would you use if you wanted to calculate the pressure of the sample?

Accepted Answer

Ideal Gas Law relates pressure, volume, temperature, and number of moles of a gas, so it can be used to calculate pressure if volume, temperature, and number of moles are known. Boyle's Law relates pressure and volume of a gas at constant temperature, Charles's Law relates volume and temperature of a gas at constant pressure, and Law of Combining Volumes relates volumes of gases in a chemical reaction.

Question 6

Most organic solvents are toxic,but supercritical fluids are generally regarded as safe.

Accepted Answer

Supercritical fluids, such as carbon dioxide, are generally considered safe to use as solvents because they have low toxicity, low flammability, and are non-reactive. They are also easy to remove from the extracted material, making them a popular choice for industries such as food and pharmaceuticals.

Question 7

Use the ideal gas law to calculate the temperature when 0.300 mol of nitrogen gas at 1.40 atm pressure occupies a volume of 11.2 L.:R = 0.0821 L* atm/(K*mol).

Accepted Answer

The ideal gas law is PV=nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature.

Rearranging the equation to solve for T, we get:

T=PV/nR

Substituting the given values, we get:

T = (1.40 atm) x (11.2 L) / (0.300 mol x 0.0821 L*atm/(K*mol))

T = 637 K

Therefore, the answer is B) 637 K.

Question 8

Carbon dioxide is an example of a supercritical fluid.

Accepted Answer

Carbon dioxide can exist as a supercritical fluid at a temperature and pressure above its critical point, where it has properties of both a gas and a liquid.

Question 9

The conditions for standard temperature and pressure (STP)are 1 atm pressure and 0°C.

Accepted Answer

This is the correct definition of standard temperature and pressure (STP) in chemistry.

Question 10

Supercritical fluids require the use of special equipment to control the temperatures and high pressures needed for their use.

Accepted Answer

Supercritical fluids require specific equipment like high-pressure vessels, pumps, and temperature control systems to achieve the necessary conditions for their use. These conditions are often beyond the range of standard laboratory equipment. Therefore, specialized equipment is required to work with supercritical fluids.

Question 11

Why are the melting points of ionic compounds higher than the melting points of molecular compounds?

Accepted Answer

The answer of Why are the melting points of ionic...

Question 12

A solution is a heterogeneous mixture.

Accepted Answer

A solution is a homogeneous mixture where the solute is uniformly distributed within the solvent.

Question 13

A covalent bond is weaker than a hydrogen bond.

Accepted Answer

Covalent bonds are stronger than hydrogen bonds. Covalent bonds involve the sharing of electrons between atoms, while hydrogen bonds involve the attraction between a hydrogen atom bonded to an electronegative atom and another electronegative atom.

Question 14

Temperatures must be converted to the Celsius temperature scale when Charles's Law is used.

Accepted Answer

The answer of Temperatures must be converted to the Celsius...

Question 15

In the ideal gas law equation,PV = nRT,R is known as

Accepted Answer

R is the universal gas constant, which relates the properties of an ideal gas such as pressure, volume, temperature, and number of moles.

Question 16

The phrase "like dissolves like" means that a polar substance will dissolve readily in a polar solvent.

Accepted Answer

The phrase "like dissolves like" implies that substances with similar chemical polarities and intermolecular forces will dissolve in each other. Thus, a polar substance will dissolve easily in a polar solvent because they have similar polarities and intermolecular forces.

Question 17

Melting is the change from the ________ state to the ________ state.

Accepted Answer

The answer of Melting is the change from the ________...

Question 18

The ideal gas law can be used to determine a new volume for a gas when its temperature is changed.

Accepted Answer

The answer of The ideal gas law can be used...

Question 19

Supercritical water and scCO₂ are "generally regarded as safe" by the U.S.Food and Drug Administration and are often used in the food industry.

Accepted Answer

Supercritical water and scCO₂ are indeed classified as GRAS (Generally Recognized as Safe) by the FDA and are commonly used in the food industry for extraction, sterilization, and decaffeination processes.

Question 20

It requires more energy to melt one mole of an ionic compound than one mole of a molecular compound.

Accepted Answer

Ionic compounds have strong electrostatic forces of attraction between their cations and anions, which makes these compounds harder to melt than molecular compounds. In contrast, molecular compounds have weaker intermolecular forces of attraction between their molecules, making them easier to melt. Therefore, more energy is required to break the strong ionic bonds in an ionic compound than the weaker intermolecular forces in a molecular compound, making the statement true.

Quiz 6: Gases, Liquids, Solids, and Intermolecular Forces