High School Chemistry : Phases of Matter

Study concepts, example questions & explanations for High School Chemistry

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Example Questions

Example Question #1 : Using Charles's Law

 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 

Possible Answers:

Correct answer:

Explanation:

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.

Example Question #2 : Using Charles's Law

Which law is the following formula?

Possible Answers:

Charles's law

Combined gas law

Boyle's law

Gay-Lussac's law

Ideal gas law

Correct answer:

Charles's law

Explanation:

Charles's law defines the direct relationship between temperature and volume. When the parameters of a system change, Charles's law helps us anticipate the effect the changes have on volume and temperature.

Boyle's law relates 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:

Example Question #3 : Using Charles's Law

A canister of gas has a volume of  at . What volume will the gas occupy at  if the pressure remains constant?

Possible Answers:

Correct answer:

Explanation:

Charles's law of gases indicates that, at a constant pressure, the volume of a gas is proportional to the temperature. This is calculated by the following equation:

Our first step to solving this equation will be to convert the given temperatures to Kelvin.

Using these temperatures and the initial volume, we can solve for the final volume of the gas.

Example Question #4 : Using Charles's Law

A gas occupies a volume of  at . At what temperature, in Kelvin, will the volume of the gas be

Possible Answers:

Correct answer:

Explanation:

Charles's law of gases indicates that, at a constant pressure, the volume of a gas is proportional to the temperature. This is calculated by the following equation:

Our first step to solving this equation will be to convert the given temperature to Kelvin.

Using this temperature and the given volumes, we can solve for the final temperature of the gas.

Example Question #5 : Using Charles's Law

The graph depicted below represents which of the gas laws?

Charles__law_graph

Possible Answers:

Newton's third law

Gay-Lussac's law

Charles's law

Boyle's law

Correct answer:

Charles's law

Explanation:

The graph shows that there is a directly proportional relationship between the volume of a gas and temperature in Kelvin when kept at a constant pressure. This is known as Charles’s law and can be represented mathematically as follows:

Gay-Lussac's law shows the relationship between pressure and temperature. Boyle's law shows the relationship between pressure and volume. Newton's third law is not related to gas principles and states that for every force on an object, there is an equal and opposite force of the object on the source of force.

Example Question #1 : Using Charles's Law

A balloon filled with room temperature air () has a volume of . The balloon is taken outside on a hot summer day where the temperature is . What will the volume of the balloon be after it is taken outside?

Possible Answers:

Correct answer:

Explanation:

We expect the volume to increase since volume and temperature are directly proportional. We know that if we heat something the material will expand so we shouldn't get a value that is smaller than our initial volume. Charles Law says that

where the stuff on the left is the initial volume and temperature and the stuff on the right is the final volume and temperature. First off, we MUST convert the temperatures to Kelvin to use Charles Law. This gives

Solving for the final volume,

Example Question #1 : Using Boyle's Law

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 ?

Possible Answers:

Correct answer:

Explanation:

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.

Example Question #1 : Using Boyle's Law

What law is the following formula?

Possible Answers:

Gay-Lussac's law

Boyle's law

Combined gas law

Ideal gas law

Charles's law

Correct answer:

Boyle's law

Explanation:

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:

Example Question #3 : Using Boyle's Law

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?

Possible Answers:

Correct answer:

Explanation:

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.

Example Question #4 : Using Boyle's Law

The graph depicted here represents which of the gas laws?

Boyle_s_law_graph

Possible Answers:

Boyle's law

Charles's law

Gay-Lussac's law

Hund's law

Correct answer:

Boyle's law

Explanation:

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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