Question

I have a question about the concept of molar volume of a gas, which is defined as the volume occupied per mole of molecules of the gas.

I don't know details about what a gas is at a deep level, but from high school level knowledge, gases expand to fill the volume they are contained in.

If we have one mole of a gas in a balloon in a huge room at sea level at a location at some standard temperature (0 degrees C), and we release the gas from the balloon, what can we say about the volume the gas will occupy? Is it really the molar volume?

How does that go with the notion that a gas expands because molecules are moving very fast and chaotically at a relatively large distance from each other?

I can understand intuitively, from everyday experience, what a molar volume of a liquid would be (at specific conditions of temperature and atmospheric pressure), because I can see the liquid and how much volume it occupies.

Does the same thing occur with gases? If we have a gas that is red, will it have a fixed volume (the molar volume)?

Answer 1

The molar volume of a gas is the volume occupied by one mole of the gas at standard temperature and pressure (STP), which is 0°C and 1 atm pressure. At STP, one mole of any gas occupies a volume of 22.4 liters. Gases can expand further if not at STP due to changes in temperature and pressure. The molar volume is a useful concept in stoichiometry.

Step-by-step explanation:

The molar volume of a gas is the volume occupied by one mole of the gas. At standard temperature and pressure (STP), which is 0°C and 1 atm pressure, one mole of any gas occupies a volume of 22.4 liters. This means that if you release one mole of gas from a balloon in a huge room at sea level at STP, the gas will occupy a volume of 22.4 liters. Although gases are known to expand and fill the volume they are contained in, the molar volume is a specific value that applies only at STP. Gases can expand further if not at STP due to changes in temperature and pressure. At STP, the molar volume is constant for any gas, regardless of its color or other physical properties. The molar volume of a gas is a useful concept in stoichiometry, as it allows for conversions between moles and volumes of gases at STP.