3B Scientific Boyle's Law Apparatus User Manual

3B SCIENTIFIC® PHYSICS

U17210 Boyle’s law apparatus

Instruction sheet

5/03 ALF

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2

43 5

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®

1 Manometer

2 Handscrew for the metering valve

3 Working cylinder with protective cylinder

4 Piston with O-rings

5 Scale

6 Rotary knob with threaded rod

This apparatus is used for the experiment-based deter­mination of the relationship between the volume and
the pressure of a gas (air) at constant temperature (Boyle’s
law).

1. Description, technical data

The apparatus consists of an enclosed plexi-glass cylin­der with graduated scale to determine volume and a
flange-mounted manometer for pressure readings and
includes an aeration and de-aeration valve. By turning
the knob the threaded rod moves the piston up an down
inside the cylinder thus varying the volume. This permits
the generation of over- and underpressure. Two O-rings
attached to the piston seal off the air. These are lubri­cated with a small amount of silicon oil. For safety rea­sons the power cylinder is encased in an additional plexi­glass cylinder.

Power cylinder:

Length: 300 mm
Diameter: 40 mm (interior)
Piston: 30 mm x 40 mm Ø

Scale:

Length: 250 mm
Scale div.: 5 mm

Manometer:

Pressure range: –10 N/cm² - 30 N/cm²
Diameter: 100 mm

2. Operation

Perform an experiment to verify Boyle’s law which states
that for a given mass of gas (air) at a constant tempera­ture the product made up of the volume and the pres­sure is constant.
The volume of the air column is computed out of the
product of the cylinder’s cross-section and the length of
the air column. As the cross-section is a fixed variable,
the change in volume can only be expressed by varying
the length of the air column.

• Ventilate the cylinder by turning the hand valve screw
to the left.

• Set the piston to the 25 cm mark. If the piston is stuck
the best remedy is to turn it slightly right to left, so
that the O-rings come into contact with the silicone
oil.

• Close the valve. The manometer gage pointed indi­cates an initial pressure of 1.

• Before each pressure reading tap your finger softly
against the manometer to make sure that the pointer
is on the right setting.

• Turn the rotary knob to slide the piston to the 24 cm
mark and read off and note down the next pressure
level.

• Repeat the procedure in 1 cm steps.

• Enter all the values into a graph (see Figure).

• Proceed accordingly for the case that Boyle’s law is to

be verified for decreasing pressure. Start here with an
air column length of 7 cm.

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3. Measurement example

Over 10 N/cm

2

Vpp x V

25 10.0 250.0
24 10.3 247.2
23 10.8 248.4
22 11.2 246.4
21 12.0 252.0
20 12.5 250.0
19 13.2 250.8
18 14.0 252.0
17 15.0 255.0
16 16.0 256.0
15 17.0 255.0
14 18.3 256.2
13 19.8 257.4
12 21.2 254.4
11 23.2 255.2
10 25.5 255.0
9,0 28.5 256.5

8.5 30.0 255.0

Below 10 N/cm

2

V p p x V

7 10 70.0
8 8.9 71.2
9 7.9 71.1
10 6.9 69.0
11 6.1 67.1
12 5.5 66.0
13 5.1 66.3
14 4.6 64.4
15 4.5 67.5
16 4.1 65.6
17 3.5 59.5
18 3.3 59.4
19 3.1 58.9
20 3.0 60.0
21 2.9 60.9
22 2.7 59.4
23 2.5 57.5
24 2.3 55.5
25 2.1 52.5

Total 4552.5

10

2

p(N/cm )

5

0

4552.5

/18 = 252.9

10 15 20

7

p > 10 N/cm²

Average

1% = 2.53

Total 1201.8

Average

1% = 0.63

25

V

1201.8

/19 = 63.25

30

25

p

20

15

10

5

10 15 20 25

V

p < 10 N/cm²

3B Scientific GmbH • Rudorffweg 8 • 21031 Hamburg • Germany • www.3bscientific.com • Technical amendments are possible

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