Gay-Lussac's Law


Gay-Lussac's Law was named after a French chemist named Joseph Louis Gay-Lussac. In the Gay-Lussac's Law the volume, moles of gas, and type of gas are usually kept constant, while the temperature and pressure are manipulated to see the relationship between them. The pressure and temperature both depend on the number of collisions between the molecules.


1. Obtain and wear goggles.

2. Prepare an ice-water bath.

4. Prepare a room water bath.

5. Prepare a hot water bath.

6. Prepare the Temperature Probe and Gas Pressure Sensor for data collection.

a.Plug the Gas Pressure Sensor into CH1 and the Temperature Probe into CH2 of the computer interface.

b.Obtain a rubber-stopper assembly with a piece of heavy-wall plastic tubing connected to one of its two valves. Attach the connector at the free end of the plastic tubing to the open stem of the Gas Pressure Sensor with a clockwise turn. Leave its two-way valve on the rubber stopper open (lined up with the valve stem) until Step 9.

c.Insert the rubber-stopper assembly into a 125 mL Erlenmeyer flask. Important: Twist the stopper into the neck of the flask to ensure a tight fit.

d.Close the 2-way valve above the rubber stopper—do this by turning the valve handle so it is perpendicular with the valve stem itself. The air sample to be studied is now confined in the flask.

7. Prepare the computer for data collection by opening the file “07 Pressure-Temperature” from the Chemistry with Computers folder of LoggerPro.

8. Click collect to begin data collection.

9. Collect pressure vs. temperature data for your gas sample:

a.Place the flask into the ice-water bath. Make sure the entire flask is covered. Stir.

b.Place the temperature probe into the ice-water bath.

c.When the pressure and temperature readings displayed in the meter stabilize, click keep. You have now saved the first pressure-temperature data pair.



Pressure in kPa- 92.52, 95.66, 104.08

Temp in C- 10.1, 20.4, 44.9

Temp in K- 283.053, 293.449, 317.919

Constant- .3374, .3259, .3274

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Graph of Data

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In Gay-Lussac's Law we discovered that the pressure and temperature are directly related. Directly related means that when one either increases or decreases, the other will do the same. This happens because both the temperature and pressure, when at a constant volume, depend of the collisions of the molecules of gas, so when there is more collisions the temperature will increase along with the pressure as well. So when we placed the flask into warmer water, increasing the temperature, the pressure also increased.