Graphing data is another way scientists (you) can analyze data collected from experiments. With your partner, learn how to create and interpolate a graph. Below is a tutorial to assist you.

Instructions: Record the answers to the questions below in your lab packet.

1. Create a graph for each set of data you collected. When you are finished compare them with the one here.
    
2. Does the general shape of your graphs stay the same ?
    
3. What conclusion can you make from comparing your graphs with each other ?
    

Scientists can learn more about how gases behave by analyzing the mathematical patterns in the numbers. In your lab packet record the answers to the questions below. Return to one of your data tables and see if you can find any additional patterns from the numbers.

1. Draw a third column on your data table to the right of the Pressure column,and label it P x V.
    
2. Multiply all the pairs of pressure and volume values and put them in your new column.
    
3. What do you notice about all of the products you have just created?
    
4. Check with your classmates on their results. How are they the same? How are they different? Can you explain the differences?

Let's go back to the first data table in which you created the P x V column. If any pair of pressure and volume values multiplied together always give the same constant value, then we ought to be able to make a mathematical relationship.

P₁ and V₁ represent the first set of conditions and P₂ and V₂ represent the second set of conditions.

This mathematical relationship is called Boyle's Law (Remember Robert Boyle?). This relationship is only true if we use data collected at the same temperature.

This relationship allows us to do a problem like the following:

 

If the pressure of 3.5 Liters of air inside a volleyball is 800 mm Hg, and someone hits the ball during a serve and causes the volume to momentarily decrease to 3.0 Liters, what will be the new pressure during that instant?
 

Additional Analysis Questons

1. During the up-stroke of the piston of a lawn mower engine, the volume inside is greatly reduced. What effect does this have on the pressure of the gases inside?

2. You repaired a leak in your bike tire and your friend offered to let you connect a hose from one of his tires to the repaired tire. From what you have learned in this lesson would you expect to be able to inflate your tire? Give your reasons.

Gases have been scientifically investigated for years, starting with Robert Boyle's work in the 1600's. Robert Boyle did many experiments with gases, and is well known for his discovery of "Boyle's Law." The work of Robert Boyle and other scientists led to the "Gas Laws."