Balloon Lab
Purpose: The air that you are breathing is a gas that is made up of about 78% nitrogen gas (N2), 20% oxygen gas (O2), and 2% of a combination of other gases. The purpose of this experiment is to study the relationship between two of the gas variable that we have discussed in class while keeping the other two constant. From this relationship, you will come up with a gas law. We will assume that the air that we are using in this experiment is at a constant pressure measured to be 765 mmHg.
Materials: 1. heating apparatus with test tube, test tube clamp, and 250-mL beaker
2. thermometer
3. ruler (be careful not to burn it)
4. balloon
5. ice water bath
Procedure:
1. Obtain a test tube and secure the balloon to the top as demonstrated in lab (be sure
that your test tube is not chipped, stretch out the balloon, use glycerin if necessary)
2. Set up the heating apparatus with the clamped test tube in as much of the water bath as
possible – record the initial temperature of the water and the initial distance from the top
of the clamp to the top of the balloon
3. Begin heating the water – record the distance between the top of the clamp and the top
of the balloon every five degree interval
4. Keep taking measurements until the temperature of the water reaches 75oC and them
remove the test tube clamp from the ring stand and hold the test tube in ice water – record
observations
5. Remove the balloon from the test tube and throw it in the trash. Repeat the procedure
for a second trial
Data: Make a data table for both trials with the temperature measurements in degrees
Celsius and the corresponding length measurements in millimeters along with any
observations
Analysis: Plot the Kelvin temperature on the x-axis versus the length measurement on
the y-axis for each trial (don’t forget units and labels on the graph)
Conclusions: questions to come on the next class day
Balloon Lab Name:______
Conclusions: Answer in complete sentences where applicable and don’t forget units, sig digs, and work for partial credit on mathematical problems.
1. What are the two variables being manipulated and what are the two variables held constant in this experiment? (refer to the purpose)
2. Based on your results, write a complete gas law accounting for all four variables in the same format as Boyle’s Law and Gay-Lussac’s Law.
3. Write a mathematical formula for this gas law.
4. What is the pressure of the gas in this lab in atm and kPa?
5. A gas with a pressure of 180 kPa is heated to a new temperature of 309 K and a new pressure of 265 kPa. What was the original temperature of the gas if volume and amount remain constant?
6. A gas at STP changes to a new volume of 955 mL and a new pressure of 6.73 atm. What was the original volume of this gas in mL if the temperature and amount remain constant?
7. 2400 mL of a gas is heated from 295 K to 327 K. What is the new volume of the gas if the pressure and amount of the gas remain constant?