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r.boyleBoyle's Law Mini-Labr.boyle

I completed this lab with my grade 11 university Chemistry class.  I had the students complete the lab and analysis.  The students were then able to tell me the relationship between volume and pressure.

Time required:

Half a period- whole period
depends if you want to give them time to complete the anaylsis in class or for homework.

This lab is taken from the textbook Chemistry 11 by McGraw-Hill Ryerson.   This lab is found on page 430-431


The Relationship between the Pressure 

and the Volume of a Gas

 

Purpose:

To allow students to discover the relationship between the pressure and the volume of a gas at a constant temperature.

 

Materials:

Thin stem plastic pipette with bulbpipette

Small C-clampc-clamp

Metric ruler (with mm)

Propane torch

Craft stick

Coloured water

 

Safety:

 

Procedure:

  1. Squeezing the bulb, draw enough coloured water into the pipette so that the water fills the bulb and extends about 2-3 cm down the stem.  The rest of the stem should be filled with air.
  2. Have your teacher melt the open end of the pipette and seal it using tongs (flat).  Allow the pipette to cool before proceeding.
  3. Copy out the data table into your notes.

P

(# of turns)

V (mm)

 

1/V (mm)

 

P x V (turns x mm)

 

0

 

 

 

.5

 

 

 

1

 

 

 

1.5

 

 

 

Etc.

 

 

 

  1. Break a craft stick in two.  Place one half of the stick on either side of the pipette bulb.  Tighten a small C-Clamp around the bulb of the pipette so that the clamp just holds the bulb snugly.
  2. Using the ruler measure the length of trapped gas (the volume) in mm.  Record this volume as the volume at 0 turns.
  3. Increase the pressure on the bulb by turning the handle of the clamp one half turn.  Record the volume of the trapped gas.
  4. Repeat step 6 until you have made a least 10 half turns.
  5. Complete the data table.  Calculate an average value for the P x V column
  6. Plot a graph of P(y-axis) versus V(x-axis)
  7. Plot a graph of P(y-axis) versus 1/V(x-axis)

 

Analysis:

  1. What is the independent variable in this investigation? What is the dependent variable?
  2. What relationship exists between volume and pressure, based on the data collected and the graphs produced?
  3. Express this relationship mathematically. 
  4. Calculate the slope of P vs. 1/V graph.  How does this value compare with the average P x V value? Of what significance are these two values?

 

Quick Explanation:

The first plot should be a curved line(see below).

The second plot should be the straight line (see below).

The values of the slope of P vs. 1/V and P x V should be the same.  

graphs