1. Mole-Volume Relationships- Gases The volumes of one mole of different solid and liquid substances are not the same (water vs. glucose). One mole of glucose is much larger than 1 mole of water. Unlike liquids and solids, the volumes of moles of gases are much more predictable under the same physical conditions.

2. Mole-Volume Relationships- Gases The volume of a gas varies with a change in temperature or a change in pressure. Because of this variation, the volume of a gas is usually measured at a standard temperature and pressure (STP). Standard Temperature and Pressure: Temperature is 0°C 101.3 kPa, or 1 atmosphere (atm) At STP, 1 mole of any gas occupies a volume of 22.4L (equal to 11, 2-liter soda bottles full of liquid) 22.4 L is known as the molar volume of a gas and is measured at STP

3. Standard Temperature and Pressure (STP) Temperature is 0°C 101.3 kPa, or 1 atmosphere (atm) At STP, 1 mole of any gas occupies a volume of 22.4L (equal to 11 2-liter soda bottles full of liquid) 22.4 L is known as the molar volume of a gas and is measured at STP

4. Because 1 mol of any substance contains Advogadro’s number of particles, 22.4 L of any gas at STP contains 6.023 x 10 23 representative particles of that gas. Why do gases need to be at STP in order for this to hold true? How does temperature affect the volume of a gas? increase temperature: particles move faster and take up more space; decrease temperature: particles move slower and take up less space

5. How does pressure affect the volume of a gas? increased pressure pushes the particles closer together and decreases the volume, while decreased pressure allows the particles to spread out and increases the volume

6. Examples Determine the volume, in liters, of 0.60 mol SO 2 gas at STP Knowns: Unknowns: Calculate:

7. The density of a gaseous compound containing carbon and oxygen is 1.964 g/L at STP. Determine the molar mass of the compound. Knowns: Unknowns: Calculate: