Volume vs. Temperature for a Gas (Charles' Law I)

 Volume vs. Temperature Relationship

In this lab, we find the relationship between volume and temperature. We use a syringe connected air-tight to the opening of a flask to measure changes in volume. Submerging the flask into a large beaker of water with different temperatures will cause different volume changes in the volume of the flask-syringe system.

The first thing we needed to find was the volume of the flask. To do this, we measured the mass of the empty flask (with stopper and tubing). Next we filled the flask and tubing with water and measured the mass again. The difference between these masses gives us the mass of the water. Now, since we know the mass of the water and the density of water, we can rewrite the density formula and solve for volume. This gives tells us that the volume inside the flask and tubing is 139.2 cubic centimeters (cc).

In this lab, we find the relationship between volume and temperature. We use a syringe connected air-tight to the opening of a flask to measure changes in volume. Submerging the flask into a large beaker of water with different temperatures will cause different volume changes in the volume of the flask-syringe system.

Now we finish our set-up by connecting the syringe to the flask. We fill a beaker with water and connect the thermometer for data collection. We also obtain ice and hot water so that we can vary the temperatures of the water in the beaker.

The flask is submerged at a cold temperature and the syringe plunger begins to move down. The gas inside the system begins to cool and since pressure is constant, the volume goes down.

Three measurements were taken for temperature (T in *C) and for volume of the syringe (V in cc). All of the other columns in this chart were calculated. The temperature Kelvin was taken by adding 273.15 to the temperature Celsius measure. The volume of the flask was measured as explained earlier. The total volume was calculated by adding the volume of the flask plus the volume of the syringe once it had stopped moving (once the volume was stabilized). 

Using the table created, we constructed a graph that models Volume vs. Temperature. Excel was used to plot points, add a trendline, and find the equation of the line. From this graph, it is evident that the relationship between volume and temperature is linear. In other words, volume is proportional to temperature.
However, volume does not equal temperature. The temperature is multiplied by a coefficient which can be found by the slope of the line. The coefficient is 0.6494 cm^3/K, or in SI units, 6.494 X 10^-7 m^3/K.