This derivation of the Ideal Gas Equation is useful in determining the molar mass of an unknown gas. Boundless vets and curates high-quality, openly licensed content from around the Internet.
This particular resource used the following sources:. Skip to main content. In association with Nuffield Foundation. Use this demonstration to practise weighing gases to calculate their relative molecular masses using the ideal gas equation.
In this experiment, students observe as different gases are weighed using a gas syringe of known volume. Students then use the ideal gas equation to calculate the number of moles and hence the relativel molecular mass RMM of the gas. Careful manipulation is needed to obtain acceptable results.
In this demonstration, the relative molecular masses of various gases are determined by weighing containers before and after they are used to collect the gases.
This is most likely to be done as a teacher demonstration. Teachers of advanced students may wish to consider the possibility of a student practical for students with good manipulative skills, using appropriate gases. The preparation of bags containing different gases, and the modification of the syringes, should be done before the lesson, as these procedures may take a considerable time.
The demonstration itself should then take about 10 minutes for each gas used. The syringe may be of capacity 50 cm 3 or cm 3 , and should be gas-tight when tested with the nozzle blocked with a finger, and have a freely moving plunger.
There should be no change in the volume reading if, when it contains 50 cm 3 or cm 3 of air, the plunger is pushed in and pulled out by 10 cm 3 and then released. Assume the gas is ideal. Then the mass of the gas divided by the moles will give the molar mass.
The calculated molar mass gives a reasonable formula for dinitrogen monoxide. The ideal gas law can be used to find the density of a gas at conditions that are not standard. Calculate the number of moles of gas contained within a bouncy house with a volume of The ideal gas equation enables us to examine the relationship between the non-constant properties of ideal gases n , P, V, T as long as three of these properties remain fixed.
For the ideal gas equation, note that the product PV is directly proportional to T. The ideal gas equation is a valuable tool that can give a very good approximation of gases at high temperatures and low pressures.
Interactive: Pressure Equilibrium : There are gases on both sides of a moveable barrier piston , which stays in the same place more or less when you run the model because the gas pressure on the piston is in equilibrium. Add purple gas molecules and watch what happens to the piston. Reset the model. Now add yellow gas molecules. What happens to the piston?
Try heating or cooling the gas molecules. Explain the change in equilibrium with each change. Which has a greater effect on equilibrium — changing the number of gas molecules or changing the temperature? Interactive: The Temperature-Pressure Relationship : Explore the relationship between the temperature of a gas and the pressure it exerts on its container. A reformulation of the Ideal Gas Equation involving density allows us to evaluate the behaviors of ideal gases of unknown quantity.
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