IdealGasLawMiniLab

Introduction

The Ideal Gas Law is for problems where you only have one condition and you are given three of the four parameters. To solve the unknown parameter, you use the equation, PV=nRT, where R=0.08206(l-atm)/(mole-K).

So let's try to determine the number of moles of a gas in a balloon knowing all the other parameters.

Directions

1. Get a 250ml beaker and fill it with about 100.ml of water. Record the volume of water to sig fig of beaker marks.
2. Get a balloon and weigh it on scale.
3. Blow it up so it just fits inside beaker.
4. With your hands on the top of the balloon force the balloon down into the water until the top of the balloon is right at the surface of the water.
5. While holding the balloon in this location, record the new volume of the water.
6. In the corner of the room nearest the white board, you need to record the barometric pressure from the barometer.
7. On each side of the demonstration table, there is a thermometer where you can record the air (gas) temperature.
8. dry off the balloon and weigh it on balance (in g):

Data Table

• Mass of balloon (in g):
• Mass of blown-up balloon (in g):
• Volume of water (ml):
• Volume of water & balloon (V by displacement)(ml):
• Temperature of gas(room):
• Gas pressure or barometric pressure (mmHg):

Calculations

• Volume of gas in balloon (ml):
  

• Mass of gas (in g):
• Assuming air is all N₂, calculate the number of moles in balloon:
  

• Using ideal gas equation, calculate (on back of paper) the number of mole of the gas.