5.1 - Gas Pressure and Its Measurements
Define Pressure and its units.
oPressure is the force exerted per unit area of surface.
oThe units are: Pascal, Atmosphere, mmHg
Convert units of pressure.
oPascal (Pa) - kg/(mXs^2)
oAtmosphere (atm) - 1 atm = 1.01325x10^5 Pa, which is about 100 kPa
ommHg - 760 mmHg = 1 atm
5.2 - Empirical Gas Laws
Express Boyle's Law in words and as an equation.
oBoyle's Law is the volume of a sample of gas at a given temperature varies
immersely with the applied pressure.
oPV=constant (for a given amount of gas at a fixed temperature)
Use Boyle's Law.
oYou can use it to calculate the volume occupied by a gas when the pressure
changes.
oTake a 50.0-L gas cyliner of oxygen. The pressure of gas in the cylinder is 15.7 atm
at 21 deg C. What volume of oxygen can you get from the cylinder at 21 deg C if the
atmospheric pressure is 1.00 atm?
P1V1=P2V2
P1=15.7 atm -- V1=50.0 L -- P2=1.00 atm -- V2=?
P1/P2 * V1 = V2
15.7atm/1.00atm * 50L = 785-L
Express Charles's Law in words and as an equation.
oCharles's Law is the volume of a sample of gas at a constant pressure is directly
proportional to the absolute temperature.
oV/T=constant, where V is volume and T is temperature
Use Charles's Law.
oThe total volume of oxygen that can be obtained from a particular tank at 1.00 atm
and 21 deg C is 785 L. What would the volume of oxygen be if the temperature had
been 28 deg C?
V1/T1 = V2/T2
V1=785L -- T1=21 deg C (294K) -- V2=? -- T2=28 deg C (301K)
V1 x T2/T1 = V2
785L * 301K/294K = 804 L
Express the Combined Gas Law as an equation.
oV=constant x (T/P) or PV/T=constant
State Avogadro's Law.
oAvogadro's Law is equal volumes of any two gases at the same temperature and pressure
contain the same number of molecules.
Define Standard Temperature and Pressure (STP).
oSTP is the reference conditions for gases chosen by convention to be 0 degC and 1 atm
pressure.
5.3 - The Ideal Gas Law
