this report made by koya university student of chemical engineering (shwan sarwan ).

1. Faulty of Engineering
School of Chemical&Petroleum Engineering
Chemical Engineering department
Laboratory of thermodynamics
EXPERIMENT NUMBER TWO
Boyles law (expansion)
Instructor: Mr rebwar&Mr umer
Author Name: shwan sarwan sadiq
Experiment Contacted on: 29/oct/2013
Report Submitted on: 12/nov /2013
Group:b

2. The aim of this experiment:
The purpose of Boyle's law is to set up a relationship
between the pressure and the volume of a gas.
The law states that as the pressure of a gas
increases,its volume decreases, and vice-versa.

3. Introduction
The ideal gas equation (PV=nRT) provides a valuable model of the
relations between volume, pressure, temperature and number of
particles in a gas. As an ideal model it serves as a reference for the
behavior of real gases. The ideal gas equation makes some
simplifying assumptions which are obviously not quite true. Real
molecules do have volume and do attract each other. All gases
depart from ideal behavior under conditions of low temperature
(when liquefaction begins) and high pressure (molecules are more
crowed so the volume of the molecule becomes important).
Refinements to the ideal gas equation can be made to correct for
these deviations.
Reference 1

4. Theory:
The kinetic theory of gases (also known as kinetic-molecular
theory) is a law that explains the behavior of a hypothetical ideal
gas. According to this theory, gases are made up of tiny particles
in random, straight line motion. They move rapidly and
continuously and make collisions with each other and the walls.
This was the first theory to describe gas pressure in terms of
collisions with the walls of the container, rather than from static
forces that push the molecules apart. Kinetic theory also explains
how the different sizes of the particles in a gas can give them
different, individual speeds
Boyle’s law states that for the pressure and volume of a gas,
when one value increases the other decreases, as long as
temperature and number of moles remain constant. Boyle's law
is summarized by the equation
PV=k
where P is the pressure of the molecules on the container, V is
the volume of the container, and k is a constant. The value of k
always stays the same so that P and V vary appropriately. For
example, if pressure increases, k must remains constant and
thus volume will decrease. This is consistent with the
.predictions of Boyle's law
Reference 2

5. EQUIPMENT and COMPONENTS USED:
(1) Tank 1 for isothermal change of state,
(2) Digital displays,
(3) 5/2-way valve for switching between
compression and expansion,
(4) Heating controller,
(5) Digital display,
(6) Tank 2 for isochoric change of state

6. Method:
switch on unit master switch (4)
open the air discharge valve (1) on the lid of
the cylinder place both 3-way valves (3) in
position 2 switch on compressor using switch
until the liquid level has reached the lowest
mark (2) on the scale on the vessel.
switch off compressor close discharge valve
on the lid of the cylinder!
start data acquisition program and make the
corresponding settings switch on compressor
at the latest at
liter residual
volume for the
air enclosed
,switch off the
compressor
open graph
measured
valued and
interpret leave
pressure
cylinder
uncharged and continue immediately with the
compression experiment

7. Discussion
the pressure would be a third of what it was before in Boyle's Law , Why does
this change?
The motion of gases also causes them to expand and fill their container, giving them a
volume equal to that of their container. If they did not strike the sides of the
container, they would continue on in a straight path.
Why are pressure and volume related then? Aren't they just two unique properties of
gases?
The link comes in how pressure is defined, and how volume affects the pressure.
Pressure is a derived unit. Pressure is force divided by a two-dimensional surface
measurement. Force is often measured in newtons (N), a unit derived from a
kilogram-meter (kg-m). Surface area is often measured in square meters or square
centimeters. A pressure unit would then be a newton per square meter (N/m2), the
Pascal (Pa). Because a Pascal is relatively small, force is often measured more
conveniently in kiloPascals (kPa).
With a gas, the pressure is exerted on the sides of the container. If there is a greater
surface area, the force will remain the same, so the pressure will go down. For
example, if a ten newton force is exerted over ten square meters, the pressure is 1
kPa. If the surface area increases to twenty square meters, the pressure is reduced to
0.5 kPa. If the surface area decreases to five square meters, the pressure is increased
to 2 kPa.
The volume of the container dictates its internal surface area for the gas. If the
volume of a gas decreases, because a gas expands to fill its container, the container's
volume must have decreased. Therefore, there is a smaller surface area, and the
pressure increases. If the volume of the gas expands, meaning a larger container, the
pressure would go down. This type of relationship is called an inverse relationship.
That's most of Boyle's law! Mathematically, this is represented as PV. Boyle's law
produces a constant, K, so extended, the formula is PV=K. However, because the
constant stays the same, additional pressures and volumes can be equated and
solutions can be found for unknowns. This equation can be a powerful tool in
solving for or converting pressures and volumes.
Reference 3

8. References :-
Reference 1
http://chemistry.bd.psu.edu/jircitano/gases.html
Reference 2
http://scuba.about.com/od/Theory/p/Boyles-Law-And-Scuba-Diving.html
Reference 3
http://library.thinkquest.org/12596/boyles.html
others from laboratory book (applied heat laboratory manual )