Electronics 10 tacostea: Determining the Ideal Gas Law

Determining the Ideal Gas Law

Two separate aluminum cans are heated and dropped into a water filled beaker:

The first can contained a small amount water.

When this can was heated, steam began to escape through the hole at the top.
Once it was dropped into the water filled beaker, it imploded and floated in the beaker.

This occurred because the volume of the liquid < volume of the steam.
Steam pushed all of the air out.
steam in the can immediately condenses
creates a partial vacuum causing can to collapse.
The only way for the pressure in the can to be equalized is for the can to collapse.

The second can was empty and heated.

Once it was dropped into the water filled beaker upside down, it appeared to do nothing.

In fact, it sucked up some of the water from the beaker.

Below are units of pressure and conversion factors.

A formula to find pressure using density, height and gravity is shown as well.

The following activity required us to hook up a syringe with a stopper to a pressure sensor. We used logger pro to measure the change in pressure per 2 cc of volume. We slowly pushed the syringe in 2 cc increments starting from 20 cc and working down. We were able to create a graph from these measurements. The best fit equation for this graph was exponential in this case. According to Boyle's law, pressure is inversely proportional to volume and the equations below can be used when solving pressure problems if the number of moles is constant and the temperature is constant.

The next activity Prof. Mason performed. He heated up a closed flask and measured the temperature change and pressure change with a thermometer and pressure sensor.

Our predictions were as follows and our fit equations matched our predictions for the general shape of the graph.

Pressure is directly proportional to temperature when volume and moles are constant.

The linear fit equation worked best in this activity.

Here we measured the increase in volume as temperature increased with a constant pressure. As temperature increases, the volume does as well. The molecules spread apart and move rapidly away from each other. The volume then increases. If the temperature decreases, the opposite occurs and the volume decreases.

Here a pressure problem was given. We were told to solve for the pressure inside of a bell upside down at a certain distance below the surface of water. We also solved for the height of the water inside of the upside down bell. We used the formula that the total pressure is equal to the sum of the partial pressures. The combined gas law was used essentially to find the height inside the bell.

The balloon problem was solved using the Ideal Gas Law. We then solved for the moles and then the grams of helium by using the known molar mass of helium. Since helium is a diatomic gas, we used He2.