UNIT # 7 Introduction Objectives Problems 1 | 2 | 3 | 4 | 5

CALCULATIONS BASED ON FORMULAE

7.6 - Molar Volume of a Gas

The volume of a gas is sensitive to both pressure and temperature. Because a gas is easily compressible, by adjusting the pressure and temperature of a gas sample, I can alter the volume that the gas sample occupies. Therefore, if the volumes of any two gas samples are to be compared, they must be under the same conditions (ie - the two gas samples MUST be at the same temperature and pressure).

A common set of conditions that is often used by scientists is called StandardTemperature and Pressure or STP. When the STP condition is implied, scientists know that the gas must be at a specific temperature and a specific pressure.

 Click to find out the specific temperature and pressure conditions at STP.

Let's take a look at Gas densities at STP.

In section 1.8 we learned about density of solids, liquids and gases. In this unit, we will focus on learning about densities of gases at STP.

 Click below to see the densities of a few common gases

For any gas at STP, when the molar mass of the gas is divided by the density of the gas, the value "22.4" is always obtained.

 Take a look at the "special" number, "22.4".

The molar volume of any gas at STP is 22.4 L.

Section 8.3
Molar Volume of a Gas and Related Calculations ..p195

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