# Lussac's Law Lab

## Background Information

Gases are made up of molecules that are in constant motion and exert pressure when they collide with the walls of their container. The velocity and the number of collisions of these molecules is affected when the temperature of the gas increases or decreases.. In this experiment, you will study the relationship between the temperature of a gas sample and the pressure it exerts.

## Step by Step Process

You need to prepare 3 different temperatures of water, prepare an ice-water bath, a room water bath, and also a hot water bath. Next you will need to get the Temperature Probe and Gas Pressure Sensor prepared for the experiment. Prepare the computer for data collection by opening the file “07 Pressure-Temperature” from the Chemistry with Computers folder of Logger Pro. Click collect to begin data collection. Collect pressure vs. temperature data for your gas sample: First collect data from the cold water and its pressure and do that for the other ones too. Click stop when you have finished collecting data. Turn off the hot plate. Record the pressure and temperature values in your data table, or, if directed by your instructor, print a copy of the table. After you get all your data collected, you must then input a best fit line into your graph to find the constant.

## Data Table and Graph

This graph shows the relationship between temperature and pressure in Lussac's Law. As you can see, the line of best fit shows the constant rise in temperature and the constant rise in pressure throughout the lab. During the lab you have change the temperature into Kelvin. This graph is in y=mx+b format. To find the constant you must input P (pressure) into y, change m into k (constant), b is equal to 0 in this equation, and change x into T (temperature). The equation ends up being k=P/T. The equation for this lab is P/T=P/T.

## Lussac's Law Math Examples

If gas is cooled from 323.0 K to 273.15 K and the volume is kept constant, what final pressure would result if the original pressure was 750 mmHg?

750mmhg = P

323K 273.15K

750mmHg x 273.15K = P

323K

204862.5 mmHg = P

323K

634.25mmHg = Pressure (Decreases)