5. • Robert Boyle in 1662 studied
the relationship between the
volume of a gas and its
pressure. Boyle varied the
pressure and noticed its effect
on the volume of the gas,
without changing its
temperature. He noticed that the
volume of the gas decreased as
the pressure exerted on it
increased. This experience is
now known as Boyle’s Law.
Syringes of all types utilize
Boyle's law on a very basic
level. Experience this
phenomenon by performing the
6. Measurable
Properties of
Gases
• 1. Pressure - the force
exerted by the gas on the
walls of its container divided
by the
• surface area of the
container.
• The common units of pressure
are the following:
• Pascal (Pa) - standard unit
of pressure under Systemé
International (SI)
• which is equivalent to a
force of one newton (1N = 1 kg
m/s2) acting on an
• area of one square meter.
• Atmosphere (atm)
• Torr
• Millimeter mercury (mm Hg)
7. Pressure can be
converted from
unit to another
using the
following
conversion:
1 atm = 760 torr =
760 mm Hg
1 torr = 1 mm Hg 1 atm = 101,325 Pa
2. Volume –defined
as the space
occupied. The
volume of the gas
is equal to the
volume of the
vessel or
container.
Common Units of
Volume: cubic
meter (m3), cubic
centimeter (cm3),
liter (L)
milliliter (mL)
3. Temperature –
defined as the
degree of hotness
or coldness.
Units: degree
Celsius (oC),
degree Fahrenheit
(oF), Kelvin (K)
8. • The temperature of a gas together with its atmospheric
pressure differ from place to place and from time to time. As the
volume of a gas is dependent on its temperature and pressure, it
is significant to have a set of standard conditions for these
quantities. This set of standard condition is named as standard
temperature and pressure or simply STP. The standard
temperature is 0 ⁰C or 273.15 K and the standard pressure is 1
atm pressure. This is the freezing point of pure water at sea level
atmospheric pressure. At STP, one mole of gas occupies 22.4 L of
volume.
9.
10. • B. The SI unit of pressure
is the Pascal, Pa, but in
the V-P relationship of
gases, it
• is necessary to be
familiarized with the
different units of pressures
and the
• corresponding values for
unit conversion.
• 1 atm = 760 torr
• 1 atm = 760 mm Hg
• 1 atm = 101,325 Pa
• 1 atm = 76 cm Hg
14. • Activity 2. Gaze,
Compare, and Conclude
Suppose we have a
theoretical gas confined
in a jar with a piston
at the top as seen in
the illustration below.
The left side indicates
the initial state while
that on the right shows
the final state after
slowly adding weights to
the top of the piston.
The unit of volume is in
cubic meters (m3), while
that of pressure is
kilopascal (kPa). The
15.
16.
17.
18.
19. Example #1: 2.00 L of a gas is at 740.0 mmHg pressure. What is its volume at standard
pressure?
Example #2: 5.00 L of a gas is at 1.08 atm. What pressure is obtained when the volume is 10.0
L?
Example #3: 9.48 L of a gas was at an unknown pressure. However, at standard pressure, its
volume was measured to be 8.00 L. What was the unknown pressure?
Example #4: If we have 6.00 cm3 of gas at a pressure of 10.0 N/cm2 and we increase the
pressure to 20.0 N/cm2, what volume will the gas occupy?
Example #5: What pressure is required to compress 196.0 liters of air at 1.00 atmosphere into a
cylinder whose volume is 26.0 liters?
Example #6: The volume of a gas is 6.10 L, measured at 1.00 atm. What is the pressure of the
gas in mmHg if the volume is changed to 9.74 L?
Example #7: At 46.0 °C a sample of ammonia gas exerts a pressure of 5.30 atm. What is the
pressure when the volume of the gas is reduced to one-eighth (0.125) of the original value at the
same temperature?
Example #8: In order to measure the volume of a piece of apparatus, a chemist filled a 750. mL
flask with 46.65 kPa pressure of gas, then expanded it into the apparatus. The final pressure was
14.95 kPa. Calculate the total volume occupied by the gas.
20. Problem #16: 4.00 L of a gas are under a pressure of 6.00 atm. What is the volume of the gas at
2.00 atm?
Problem #17: A gas occupies 25.3 mL at a pressure of 790.5 mmHg. Determine the volume if the
pressure is reduced to 0.804 atm.
Problem #18: A sample of gas has a volume of 12.0 L and a pressure of 1.00 atm. If the pressure
of gas is increased to 2.00 atm, what is the new volume of the gas?
Problem #19: A container of oxygen has a volume of 30.0 mL and a pressure of 4.00 atm. If the
pressure of the oxygen gas is reduced to 2.00 atm and the temperature is kept constant, what is
the new volume of the oxygen gas?
Problem #20: A tank of nitrogen has a volume of 14.0 L and a pressure of 760.0 mmHg. Find the
volume of the nitrogen when its pressure is changed to 400.0 mmHg while the temperature is
held constant.
Problem #21: A 40.0 L tank of ammonia has a pressure of 8.00 atm. Calculate the volume of the
ammonia if its pressure is changed to 12.0 atm while its temperature remains constant.
Problem #22: Two hundred liters of helium at 2.00 atm and 28.0 °C is placed into a tank with an
internal pressure of 600.0 kPa. Find the volume of the helium after it is compressed into the tank
when the temperature of the tank remains 28.0 °C.
