Transcript The Gas Laws - Belle Vernon Area School District

The Gas Laws
11.2
Boyle’s Law
• Boyle’s Law – the volume of a fixed
mass of gas varies inversely with the
pressure at constant temp.
• PV = k
• You can relate 2 different gases w/ k
• P1V1 = P2V2
Practice
• A sample of O2 gas has a vol of
150.00 mL when it’s P is 0.947
atm. What will the vol of the gas
be at a P of 0.987 atm if the T
remains constant?
• Make sure both P and V units are
the same!
Practice
• A balloon filled with He gas has a
vol of 500 mL at a P of 1 atm. The
balloon is released and reaches an
altitude of 6.5 km, where the P is
0.5 atm. If the T has remained
the same, what volume does the
gas occupy at this height?
Temperature
• Absolute zero – the T of -273.15 °C is
given a value of 0 in the Kelvin scale.
• K = 273.15 + °C
• Charles’ Law = the vol of a fixed
mass of gas at constant P varies
directly with the Kelvin Temp
Charles’ Law
• V = kT
•V = k
T
• V1 = V2
T1 = T2
Practice
• A sample of neon gas occupies a
volume of 752 mL at 25°C. What V
will the gas occupy at 50°C if the P is
constant?
• A sample of N2 gas is contained in a
piston w/a freely moving cylinder.
At 0°C, the V of the gas is 375 mL.
To what T must the gas be heated to
occupy a V of 500.0 mL?
Gay-Lussac’s Law
• The P of a fixed mass of a gas at
constant V varies directly with the
Kelvin T
• P = kT
P=k
T
Set K equal to get…
P1 = P 2
T1 = T 2
Practice
• The gas in a container is at a P of
3.00 atm at 25°C. Directions on
the container warn the user not to
keep it in a place where the T
exceeds 52°C. What would the P
be at 52°C?
Practice
• At 120.0 °C, the pressure of a
sample of nitrogen is 1.07 atm.
What will the pressure be at 205 °C,
assuming constant volume.
• A sample of He gas has a P of 1.20
atm at 22 °C. At what Celsius Temp
will the He reach a P of 2.00 atm,
assuming constant V.
The Combined Gas Law
• Combines Charles’, Boyle’s, and
G-L
• CGL – expresses the relationship
b/t P, V, and T of a fixed amt of
gas
PV = k P1V1 = P2V2
T
T1
T2
• T must be in Kelvin!!!!!
Practice
• A helium Balloon has a volume of
50.0 L at 25°C and 1.08 atm. What
V will it have at 0.855 atm & 10.0°C?
• A 700.0 mL gas sample at STP is
compressed to a V of 200.0 mL, and
the T is increased to 30.0 °C. What
is the new P of the gas in Pa?
• Complete S.R. on page 375 # 1-5 