Gases and Gas Laws - AP Chemistry
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Which of the following gases will diffuse the quickest through a small hole?
Which of the following gases will diffuse the quickest through a small hole?
Gases with high higher molecular weights are going to move at slower velocities. At a given temperature, all gases have the same average kinetic energy. For this to remain true, larger molecules must move slower since they have greater masses.
The gas to diffuse quickest will have the smallest molecular weight. In this case, that gas is hydrogen.
Gases with high higher molecular weights are going to move at slower velocities. At a given temperature, all gases have the same average kinetic energy. For this to remain true, larger molecules must move slower since they have greater masses.
The gas to diffuse quickest will have the smallest molecular weight. In this case, that gas is hydrogen.
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Which of the following is a physical property of gases?
Which of the following is a physical property of gases?
There are six primary properties of gases: expansion, fluidity, low density, compressibility, diffusion, and effusion.
Expansion suggests that gases have no defined shape and will expand to fill a given space, without significant intermolecular interaction. Fluidity is a property of both gases and liquids and describes the relatively low attraction between particles. This allows the gas molecules to move past one another, creating the "fluid" nature of the gas. Low density of gases is linked to gas expansion. Gases will expand to the greatest extent possible, resulting in low mass per unit volume ratios. Compressibility is also linked to expansion and the indefinite shape of the gas, essentially suggesting that the distance between particles can be reduced if pressure is increased. Diffusion and effusion are both linked to the movement of gases. Diffusion means that gases can spread out and mix within a given space, while effusion means that gases can pass through a small opening at a given rate.
Some of these properties are unique to gases, while others are shared between gases and liquids. Gases have virtually no physical properties in common with solids.
There are six primary properties of gases: expansion, fluidity, low density, compressibility, diffusion, and effusion.
Expansion suggests that gases have no defined shape and will expand to fill a given space, without significant intermolecular interaction. Fluidity is a property of both gases and liquids and describes the relatively low attraction between particles. This allows the gas molecules to move past one another, creating the "fluid" nature of the gas. Low density of gases is linked to gas expansion. Gases will expand to the greatest extent possible, resulting in low mass per unit volume ratios. Compressibility is also linked to expansion and the indefinite shape of the gas, essentially suggesting that the distance between particles can be reduced if pressure is increased. Diffusion and effusion are both linked to the movement of gases. Diffusion means that gases can spread out and mix within a given space, while effusion means that gases can pass through a small opening at a given rate.
Some of these properties are unique to gases, while others are shared between gases and liquids. Gases have virtually no physical properties in common with solids.
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Which of the following gas laws can be used to determine the total pressure of a mixture of gases?
Which of the following gas laws can be used to determine the total pressure of a mixture of gases?
Each gas in a mixture of gases exerts its own pressure independently of the other gases present; therefore the pressure of each gas within a mixture is called the partial pressure of the gas.
Dalton's law of partial pressures states that the total pressure of a mixture of gases is equal to the sum of the partial pressures of the component gases. This can be expressed mathematically as follows:
Boyle's law and Gay-Lussac's law can help determine pressure in varying volumes and temperatures, respectively, but can only be useful with regard to the total pressure of the system. The second law of thermodynamics is not related to gas properties, and states that the entropy of the universe is constantly increasing.
Each gas in a mixture of gases exerts its own pressure independently of the other gases present; therefore the pressure of each gas within a mixture is called the partial pressure of the gas.
Dalton's law of partial pressures states that the total pressure of a mixture of gases is equal to the sum of the partial pressures of the component gases. This can be expressed mathematically as follows:
Boyle's law and Gay-Lussac's law can help determine pressure in varying volumes and temperatures, respectively, but can only be useful with regard to the total pressure of the system. The second law of thermodynamics is not related to gas properties, and states that the entropy of the universe is constantly increasing.
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Which of the following is not a characteristic of gases?
Which of the following is not a characteristic of gases?
Gases are able to effuse though small pinhole openings, and diffuse into empty spaces from high to low concentrations. The kinetic energy of gas molecules is dependent on temperature. Higher temperatures cause in increase in the kinetic energy of the particles.
Gases have very low densities. Density is a measure of mass per unit volume. Since the gas molecules are spread out over a much larger distance compared to liquids and solids, their densities are very low.
Gases are able to effuse though small pinhole openings, and diffuse into empty spaces from high to low concentrations. The kinetic energy of gas molecules is dependent on temperature. Higher temperatures cause in increase in the kinetic energy of the particles.
Gases have very low densities. Density is a measure of mass per unit volume. Since the gas molecules are spread out over a much larger distance compared to liquids and solids, their densities are very low.
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A container filled with fluorine gas and neon gas and has a total pressure of 
. There are 
of fluorine gas in the container, and the fluorine gas exerts a pressure of 
.
Based on this, what is the mass of neon in the container?
A container filled with fluorine gas and neon gas and has a total pressure of
Based on this, what is the mass of neon in the container?
The partial pressures of each gas are not dependent on their masses, but the total number of moles of gas in the container. Since we know how much pressure the fluorine gas exerts on the container, we can solve for the molar fraction of fluorine gas in the container.
In other words, 62.5% of the gas in the container is fluorine gas. Knowing this, we can solve for how many moles of neon gas are in the container.
50 grams of fluorine gas is equal to 1.32 moles of fluorine gas. If this molar amount accounts for 62.5% of the gas in the container, we can solve for the total number of moles in the container:
Since there are only two gases in the container, we can solve for the number of moles of neon gas in the container.
Since there are .79 moles of neon gas, we can multiply by the molar mass and find the toal mass of the neon gas in the container:
The partial pressures of each gas are not dependent on their masses, but the total number of moles of gas in the container. Since we know how much pressure the fluorine gas exerts on the container, we can solve for the molar fraction of fluorine gas in the container.
In other words, 62.5% of the gas in the container is fluorine gas. Knowing this, we can solve for how many moles of neon gas are in the container.
50 grams of fluorine gas is equal to 1.32 moles of fluorine gas. If this molar amount accounts for 62.5% of the gas in the container, we can solve for the total number of moles in the container:
Since there are only two gases in the container, we can solve for the number of moles of neon gas in the container.
Since there are .79 moles of neon gas, we can multiply by the molar mass and find the toal mass of the neon gas in the container:
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Assume air contains 21% oxygen and 79% nitrogen.
If air is compressed to 5.5atm, what is the partial pressure of the oxygen?
Assume air contains 21% oxygen and 79% nitrogen.
If air is compressed to 5.5atm, what is the partial pressure of the oxygen?
Use Dalton's law of partial pressure:
Where 
is the partial pressure of oxygen and 
is the mole fraction of oxygen. Plug in known values and solve.
Use Dalton's law of partial pressure:
Where
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Mass density is the grams of gas per volume, while number density is the number of molecules per volume.
Which of the following has the highest number density, if each gas occupies the same volume?
Mass density is the grams of gas per volume, while number density is the number of molecules per volume.
Which of the following has the highest number density, if each gas occupies the same volume?
Divide each component by their molecular weight to obtain the number of moles. The hydrogen gas has the most moles that occupy the same volume. Remember that of the answer choices, hydrogen, and oxygen are both diatomic gasses, which needs to be taken into account when calculating the number of moles. For simplicity, let's assume we have 1L of each gas.
As an example, let's calculate the number density for oxygen to show that it is indeed less than that for hydrogen.
Divide each component by their molecular weight to obtain the number of moles. The hydrogen gas has the most moles that occupy the same volume. Remember that of the answer choices, hydrogen, and oxygen are both diatomic gasses, which needs to be taken into account when calculating the number of moles. For simplicity, let's assume we have 1L of each gas.
As an example, let's calculate the number density for oxygen to show that it is indeed less than that for hydrogen.
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of nitrogen gas are contained in a 
container. The gas exerts a pressure of 
on the container.
If pressure is kept constant, what is the final molar amount of gas present in the container if gas is added until the volume has increased to 
?
If pressure is kept constant, what is the final molar amount of gas present in the container if gas is added until the volume has increased to
Since pressure is kept constant, we can directly compare the moles of gas in the container and volume using Avogadro's law. Since moles of gas and volume are on opposite sides of the ideal gas law, the two variables are directly proportional to one another.
Avogadro's law is written as follows:
First, we will need to convert the initial mass of gas to moles. It is important to remember that nitrogen gas is diatomic!
Use this value and the given volumes to solve for the final amount of gas in the container.
Since pressure is kept constant, we can directly compare the moles of gas in the container and volume using Avogadro's law. Since moles of gas and volume are on opposite sides of the ideal gas law, the two variables are directly proportional to one another.
Avogadro's law is written as follows:
First, we will need to convert the initial mass of gas to moles. It is important to remember that nitrogen gas is diatomic!
Use this value and the given volumes to solve for the final amount of gas in the container.
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If 1.0mol of helium gas (He) at standard temperature and pressure (STP) has a volume of 22.4L, how many moles of carbon tetrachloride gas (CCl4) will be present in a container with a volume of 22.4L?
If 1.0mol of helium gas (He) at standard temperature and pressure (STP) has a volume of 22.4L, how many moles of carbon tetrachloride gas (CCl4) will be present in a container with a volume of 22.4L?
Avogadro's Law states that two gases at the same temperature and volume will have an equal number of molecules, and therefore the same number of moles.
It does not matter that helium has one atom per molecule while carbon tetrachloride has five atoms per molecule. Note that the given volume per mole of gas at STP is standard, and true for any gas. At STP, one mole of gas will always have a volume of 22.5L, regardless of its identity.
Avogadro's Law states that two gases at the same temperature and volume will have an equal number of molecules, and therefore the same number of moles.
It does not matter that helium has one atom per molecule while carbon tetrachloride has five atoms per molecule. Note that the given volume per mole of gas at STP is standard, and true for any gas. At STP, one mole of gas will always have a volume of 22.5L, regardless of its identity.
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How many neutrons are in 10 moles of aluminum?
How many neutrons are in 10 moles of aluminum?
To find the number of neutrons, we must convert the moles to atoms by multiplying the moles by Avogadro's number 
.
Now looking at the periodic table, the neutrons per atom can be found by subtracting the atomic weight by the atomic number:
Thus there are 14 neutrons in each atom of aluminum.
To find the number of neutrons, we must convert the moles to atoms by multiplying the moles by Avogadro's number
Now looking at the periodic table, the neutrons per atom can be found by subtracting the atomic weight by the atomic number:
Thus there are 14 neutrons in each atom of aluminum.
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An ideal gas exerts a pressure of 
in a 
container. The container is at a temperature of 
.
What will be the final pressure if the volume of the container changes to 
?
An ideal gas exerts a pressure of
What will be the final pressure if the volume of the container changes to
Since the volume of the gas is the only variable that has changed, we can use Boyle's law in order to find the final pressure. Since pressure and volume are on the same side of the ideal gas law, they are inversely proportional to one another. In other words, as one increases, the other will decrease, and vice versa.
Boyle's law can be written as follows:
Use the given volumes and the initial pressure to solve for the final pressure.
Since the volume of the gas is the only variable that has changed, we can use Boyle's law in order to find the final pressure. Since pressure and volume are on the same side of the ideal gas law, they are inversely proportional to one another. In other words, as one increases, the other will decrease, and vice versa.
Boyle's law can be written as follows:
Use the given volumes and the initial pressure to solve for the final pressure.
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A sample of oxygen gas has a volume of 
when its pressure is 
. What will the volume of the gas be at a pressure of 
if the temperature remains constant?
A sample of oxygen gas has a volume of
To solve this question we will need to use Boyle's law:
We are given the initial pressure and volume, along with the final pressure. Using these values, we can calculate the final volume.
To solve this question we will need to use Boyle's law:
We are given the initial pressure and volume, along with the final pressure. Using these values, we can calculate the final volume.
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A helium balloon has a volume of 
when it is at ground level. The balloon is transported to an elevation of 
, where the pressure is only 
. At this altitude the gas occupies a volume of 
. Assuming the temperature has remained the same, what was the ground level pressure?
A helium balloon has a volume of
To solve this question we will need to use Boyle's law:
We are given the final pressure and volume, along with the initial volume. Using these values, we can calculate the initial pressure.
Note that the pressure at sea level is equal to 
. A pressure greater than 
simply indicates that the ground level is below sea level at this point.
To solve this question we will need to use Boyle's law:
We are given the final pressure and volume, along with the initial volume. Using these values, we can calculate the initial pressure.
Note that the pressure at sea level is equal to
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What law is the following formula?
What law is the following formula?
Boyle's law relates the pressure and volume of a system, which are inversely proportional to one another. When the parameters of a system change, Boyle's law helps us anticipate the effect the changes have on pressure and volume.
Charles's law relates temperature and volume: 
Gay-Lussac's law relates temperature and pressure: 
The combined gas law takes Boyle's, Charles's, and Gay-Lussac's law and combines it into one law: 
The ideal gas law relates temperature, pressure, volume, and moles in coordination with the ideal gas constant: 
Boyle's law relates the pressure and volume of a system, which are inversely proportional to one another. When the parameters of a system change, Boyle's law helps us anticipate the effect the changes have on pressure and volume.
Charles's law relates temperature and volume:
Gay-Lussac's law relates temperature and pressure:
The combined gas law takes Boyle's, Charles's, and Gay-Lussac's law and combines it into one law:
The ideal gas law relates temperature, pressure, volume, and moles in coordination with the ideal gas constant:
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The graph depicted here represents which of the gas laws?
The graph depicted here represents which of the gas laws?
The graph shows that there is an inverse relationship between the volume and pressure of a gas, when kept at a constant temperature. This was described by Robert Boyle and can be represented mathematically as Boyle's law:
Gay-Lussac's law shows the relationship between pressure and temperature. Charles's law shows the relationship between volume and temperature. Hund's rule (Hund's law) is not related to gases, and states that electron orbitals of an element will be filled with single electrons before any electrons will form pairs within a single orbital.
The graph shows that there is an inverse relationship between the volume and pressure of a gas, when kept at a constant temperature. This was described by Robert Boyle and can be represented mathematically as Boyle's law:
Gay-Lussac's law shows the relationship between pressure and temperature. Charles's law shows the relationship between volume and temperature. Hund's rule (Hund's law) is not related to gases, and states that electron orbitals of an element will be filled with single electrons before any electrons will form pairs within a single orbital.
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A gas is initially in a 5L piston with a pressure of 1atm.
If pressure changes to 3.5atm by moving the piston down, what is new volume?
A gas is initially in a 5L piston with a pressure of 1atm.
If pressure changes to 3.5atm by moving the piston down, what is new volume?
Use Boyle's Law:
Plug in known values and solve for final volume.
Use Boyle's Law:
Plug in known values and solve for final volume.
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The graph depicted here represents which of the gas laws?
The graph depicted here represents which of the gas laws?
The graph shows that gas pressure varies directly with Kelvin temperature at a constant volume, as determined by Gay-Lussac. Gay-Lussac's law can be represented mathematically for a given mass of gas at a constant volume as follows:
Boyle's law shows the relationship between pressure and volume. Charles's law shows the relationship between volume and temperature. Newton's second law is not related to gases and shows the relationship between force, mass, and acceleration.
The graph shows that gas pressure varies directly with Kelvin temperature at a constant volume, as determined by Gay-Lussac. Gay-Lussac's law can be represented mathematically for a given mass of gas at a constant volume as follows:
Boyle's law shows the relationship between pressure and volume. Charles's law shows the relationship between volume and temperature. Newton's second law is not related to gases and shows the relationship between force, mass, and acceleration.
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A balloon of volume 
at 
is placed in a pressure chamber where the pressure becomes 
, determine the new volume.
A balloon of volume
Use Boyle's law and plug in appropriate parameters:
Use Boyle's law and plug in appropriate parameters:
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A gas in a 
container is at 
is compressed to a volume of 
. What is the new pressure of the container?
A gas in a
Boyle's Law is:
The initial volume (
) and pressure (
) of the gas is given. The volume changes to a new volume (
). Our goal is to find the new pressure (
). Solving for the new pressure gives:
Notice the answer has 3 significant figures.
Boyle's Law is:
The initial volume (
Notice the answer has 3 significant figures.
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of an ideal gas are contained in a 
container at a temperature of 
. The gas exerts a pressure of 
on the container.
If pressure is kept constant, what is the final volume of the gas if the temperature of the container is increased to 
If pressure is kept constant, what is the final volume of the gas if the temperature of the container is increased to
Since pressure is kept constant, the only variable that is manipulated is temperature. This means that we can use Charles's law in order to compare volume and temperature. Since volume and temperature are on opposite sides of the ideal gas law, they are directly proportional to one another. As one variable increases, the other will increase as well.
Charles's law is written as follows:
To use this law, we must first convert the temperatures to Kelvin.
Use these temperatures and the initial volume to solve for the final volume.
Since pressure is kept constant, the only variable that is manipulated is temperature. This means that we can use Charles's law in order to compare volume and temperature. Since volume and temperature are on opposite sides of the ideal gas law, they are directly proportional to one another. As one variable increases, the other will increase as well.
Charles's law is written as follows:
To use this law, we must first convert the temperatures to Kelvin.
Use these temperatures and the initial volume to solve for the final volume.
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