1.0 INTRODUCTION

This week, our group have done an experiment titled of Boyle’s Law. Boyle’s law

sometimes referred as Boyle-Marriotte law is one of many gas laws and a special case of

the ideal gas laws. Boyle’s law describes the inversely proportional relationship between

the absolute pressure and volume of gas, if the temperature is kept constant with a closed

system. The law was named after chemist and physicist Robert Boyle, who published the

original law in 1662.

Gases have various properties which can be observed with our senses including its

pressure, temperature, mass, and the volume which contains the gas. Carefully, scientific

observation has determined that these variables are related to one another and that the

values of these properties determine the state of the gas.

The mathematical equation for Boyle's law is:

where:

p denotes the pressure of the system.

V denotes the volume of the gas.

k is a constant value representative of the pressure and volume of the system.

So long as temperature remains constant the same amount of energy given to the

system persists throughout its operation and therefore, theoretically, the value of k will

remain constant. However, due to the derivation of pressure as perpendicular applied force

and the probabilistic likelihood of collisions with other particles through collision theory,

the application of force to a surface may not be infinitely constant for such values of  k, but

will have a limit when differentiating such values over a given time.

Forcing the volume V of the fixed quantity of gas to increase, keeping the gas at the

initially measured temperature, the pressure p must decrease proportionally. Conversely,

reducing the volume of the gas increases the pressure.

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Boyle's law is used to predict the result of introducing a change, in volume and

pressure only, to the initial state of a fixed quantity of gas. The before and after volumes

and pressures of the fixed amount of gas, where the before and after temperatures are the

same (heating or cooling will be required to meet this condition), are related by the

equation:

Boyle's law, Charles's law, and Gay-Lussac's law form the combined gas law. The

three gas laws in combination with Avogadro's law can be generalized by the ideal gas law.

Gasses have various properties which c[2an be observed with our senses including its

pressure, temperature, mass, and the volume which contains the gas. Carefully, scientific

observation has determined that these variables are related to one another and that the values

of these properties determine the state of the gas.

In the mid 1600’s, Robert Boyle studied the relationship between the pressure, p, and the

volume, V, of a confined gas held at a constant temperature. Boyle’s Law states that:

“For a fixed mass of ideal gas at fixed temperature, the product of pressure and volume is a

constant”

Mathematical-wise:

p×V=const

Where:

p is the pressure of the gas, and

V is the volume of the gas

A further relationship is described by Gay-Lussac Law. This law states that if a fixed

quantity of gas is contained in a constant volume, the pressure is proportional to the absolute

temperature.

p∝T V=const

The combination of both laws leads to the general gas equation:

p1V 1

T1

=p2V 2

T2

=const

For a fixed quantity of gas, the expression ( p×V )T

always remain constant.

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2.0 OBJECTIVES

The objectives of this experiments are :

1. To verifying the Boyle’s Law the following values of pressures and volumes for a

given mass of dry gas at room temperature.

2. To study of behaviour of gases that stated through Boyle’s Law.

3. To determine the relationship between volume, pressure and temperature.

4. To study the technique in using boyle’s law demonstration/PC.

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3.0 APPARATUS

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4.0 PROCEDURE

4.1 Isochoric Heating

1) The unit was switch on at master switch.

2) The air discharge valve on the lid of heatable cylinder was opened and the vessel was

set to ambient pressure.

3) The air discharge valve was then closed.

4) The required final temperature was set on the heating regulator by using the arrow

keys.

5) The heater was switch on and operated as long as necessary until the final

temperature was reached.

6) The readings of the temperature and pressure was recorded at equal time intervals

until the final temperature was reached(5-7 readings)

7) The cylinder was leave unchanged and the cooling experiment was continued

immediately

4.2 Isochoric cooling

1) The heater was switch off.

2) The air discharge valve on the lid of heatable cylinder and the vessel was set to

ambient pressure.

3) The air discharge valve was then closed.

4) The reading of the temperature was and pressure at equal intervals was recorded

while the vessel cools to ambient temperature.

5) The air discharge valve on the lid of the cylinder was opened and the vessel was set

to ambient pressure.

6) Switch off the master unit at the master unit.

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4.3 Isothermic Compression

1) The unit was switched on at the master switch.

2) The air discharge valve on the lid of the cylinder was opened halfway.

3) Both 3-way valve was place in position 1.

4) The compressor was switched on by using a switch until the liquid level has reached

the lowest mark on the scale on the cylinder.

5) The compressor was then switched off.

6) The air discharge valve on the lid of cylinder was close.

7) Switch on the compressor and the liquid will start entering the cylinder. The reading

of the pressure and volume of air inside of the cylinder was recorded as the cylinder

is filled up with the liquid.

8) The compressor was stopped once the liquid was filled up to the upper most mark on

the cylinder. The display for volume should show 1.00.

9) The cylinder was leave unchanged and the expansion experiment was continued

immediately.

4.4 Isothermic Expansion

1) The air discharge valve was opened and closed and the 3-way valve interchangeably

until ambient pressure is reached in the cylinder. The level of the liquid in the

cylinder at that time should be adjusted to be at the upper mark of the cylinder.

2) The air discharge valve was closed.

3) Both flow adjustment valve was placed in position 2.

4) The compressor was switched on and the gas volume was expanding until the

lowest mark on the scale of the cylinder was reach. The readings of the pressure and

volume of the air throughout this process was recorded at regular intervals.

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5.0 DATA AND RESULT

5.1 Isochoric Heating and Cooling

Heating

No. Time, t (min) Temperature, T (°C) Pressure, p (bar) p (bar) / T (K) (×10-3)1 1 22.0 1.06 4.812 2 28.0 1.12 4.003 3 37.1 1.17 3.294 4 48.2 1.22 2.535 5 60.5 1.25 2.076 6 71.4 1.27 1.787 7 79.0 1.27 1.61

Graph

10 20 30 40 50 60 70 80 900.95

1

1.05

1.1

1.15

1.2

1.25

1.3

pressure against temperature

pressure against temperature

pressure(bar)

temperature, T (°C)

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0 1 2 3 4 5 6 7 8

0

1

2

3

4

5

6

p/T against time

p/T against time

time,t

Cooling

No.

Time, t (min) Temperature, T (°C) Pressure, p (bar) p (bar) / T (K) (×10-3)

1 1 84.4 0.98 1.162 2 82.7 0.97 1.173 3 80.7 0.96 1.194 4 78.3 0.95 1.215 5 75.7 0.94 1.246 6 73.1 0.93 1.277 7 70.4 0.92 1.318 8 67.8 0.92 1.369 9 65.3 0.91 1.3910 10 62.9 0.91 1.4511 11 60.0 0.90 1.4912 12 58.5 0.90 1.5413 13 56.5 0.89 1.5714 14 54.7 0.88 1.6115 15 52.9 0.88 1.6616 16 51.3 0.88 1.7117 17 49.8 0.88 1.7718 18 48.3 0.87 1.8019 19 47.0 0.87 1.8520 20 45.7 0.86 1.90

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p/T

Graph

40 45 50 55 60 65 70 75 80 85 900.8

0.820.840.860.88

0.90.920.940.960.98

1

Series2

pressure against temperaturep

T

0 5 10 15 20 250

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Series2

time,t

p/T against timep/T

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5.2 Compression and Expansion

Compression

No. Volume, V (m3) Pressure, p (bar) p × V Temperature, T1 3.0 1.01 3.03 20.5

2 2.5 1.23 3.08 20.83 2.0 1.55 3.10 21.64 1.5 2.02 3.03 22.65 1.0 3.12 3.04 24.5

Graph

0.5 1 1.5 2 2.5 3 3.50

0.5

1

1.5

2

2.5

3

3.5

Series2

Graph p against V

p

V

Expansion

No. Volume, V (m3) Pressure, p (bar) p × V(nM) Temperature, T1 1.0 1.00 1.00 19.82 1.5 0.67 1.01 19.53 2.0 0.51 1.02 19.34 2.5 0.40 1 19.35 3.0 0.34 1.02 19.5

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0.5 1 1.5 2 2.5 3 3.50

0.2

0.4

0.6

0.8

1

1.2

Series2

Graph p against Vp

V

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8.0 REFERRENCE

1. Levine , Ira. N(1978) “PHYSICAL CHEMISTRY”

2. mailto:2. www.lun.edu/boyleslaw

3. THERMODYNAMICS by Yunus A. Cengel

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