Name: ________________________
Date: ______________ Period: ____
Gas Laws
Background:
In general terms, pressure conveys the idea of a force, a push
that tends to move something in a given direction. Pressure, P, is the
force, F, that acts on a given area, A.
P = F/A
We can calculate the magnitude of the atomospheric pressure
as follows: The force, F, exerted by any object is the product of its
mass, m, times its acceleration, a.
F = ma
The acceleration given by the Earth’s gravity to any object
located near Earth’s surface is 9.8m/s2. Now imagine a column of air
1m2 in cross section extending through the entire atmosphere. That
column has a mass of roughly 10,000kg. The force exerted by the
column of the Earth’s surface is:
F = (10,000kg)(9.8m/s2) = 1 x 105kg-m/s2 = 1 x 105N
The SI unit for force is kg-m/s2 and is called the Newton (N).
The SI unit of pressure is N/m2. It is given the name pascal (Pa) after
Blaise Pascal (1623-1662). Evangelista Torricelli (1608-1647) who
was a student of Galileo’s invented the barometer.
P = F = 1 x 105N = 1 x 105N/m2 = 1 x 105Pa = 1 x 102kPa
A
1m2
Name: ________________________
Date: ______________ Period: ____
Converting Units of Pressure:
Standard atmospheric pressure is the pressure sufficient to
support a column of mercury 760mm high. In SI units, this pressure
equals 1.01325 x 105Pa. Standard atmospheric pressure defines
some common non-SI units used to express gas pressures such as
the atmosphere (atm) and the millimeter of mercury (mmHg). The
latter unit is also called the torr, after Torricelli.
1 atm = 760 mmHg = 760 torr = 1.01325 x 105Pa = 101.325kPa
Practice:
A) Convert 0.357 atm to torr.
B) Convert 6.6 x 10-2torr to atm.
C) Convert 147.2kPa to torr.
Name: ________________________
Date: ______________ Period: ____
Converting Units of Pressure
1. Convert 5 atm to torr.
2. Convert 100 torr to atm.
3. Convert 52 kPa to torr.
4. Convert 562 mmHg to torr.
5. Convert 472 torr to Pa.
6. Convert 73.345 kPa to Pa.
7. Convert 670 torr to atm.
8. Convert 64 atm to kPa.
9. Convert 435 mmHg to Pa.
10. Convert 5.38 x 105 Pa to atm.