1. Aim: What is the difference between the ideal and real gases? Do now: 1. A certain gas at STP has a volume of 5 liters. What is the new volume of the given gas, if the new pressure is 5 atm and a new temperature is 500K ? 2. Hand in the homework Announcement: Quiz today Lab Tuesday

2. In the “ideal” world the gas particles would act according to a prediction. A real gas molecule has a shape and a finite size. An ideal gas molecule (imaginary) is a point with no shape and it occupies no space. A real gas molecule interacts with others. An ideal gas molecule reacts totally independent of all others. There are no ideal gas molecules, only real gas molecules. However, as the pressure becomes very small and the temperature becomes very high, real gas molecules come closer to acting like ideal gas molecules. There are no real ideal gases, but hydrogen and helium are very near to ideal behavior.

3. Disclaimers to how gases behave: 1. When temperatures becomes cold enough then the gas particles DO attract each other and become solid. (ex. Water becoming rain or snow) 2. At high pressure increased concentrations of particles lead to more frequent collisions and far greater chance of combining. Therefore, the volume occupied by gas particles is taken in consideration.

4. Important equation P is the pressure (in atms) V is the volume (in liters) n is the amount of substance of the gas (in moles) R is the gas constant (0.0820 liter atm mol -1 K -1,) T is the absolute temperature (in Kelvin)

5. 1. How many moles of gas does it take to occupy 120 liters at a pressure of 2.3 atmospheres and a temperature of 340 K?

6. 2. If I have a 50 liter container that holds 45 moles of gas at a temperature of 200 0 C, what is the pressure inside the container?

7. 3. It is not safe to put aerosol canisters in a campfire, because the pressure inside the canisters gets very high and they can explode. If I have a 1.0 liter canister that holds 2 moles of gas, and the campfire temperature is 1400 0 C, what is the pressure inside the canister?

8. 4. How many moles of gas are in a 30 liter scuba canister if the temperature of the canister is 300 K and the pressure is 200 atmospheres?

9. 5. I have a balloon that can hold 100 liters of air. If I blow up this balloon with 3 moles of oxygen gas at a pressure of 1 atmosphere, what is the temperature of the balloon?

10. ANSWERS 1)9.89 moles 2)34.9 atm 3)274.5 atm 4)243.7 moles 5)406.2 K (133.2 0 C – a very hot day to blow up balloons!)