View
225
Download
0
Category
Preview:
DESCRIPTION
Example 1:Example 1: A coke can has 5.00atm of gas at 21°C. Calculate the pressure inside the can when it is found in a warehouse during the summer at 38°C.
Citation preview
Gas Laws: Gay-Lussac’s Law and
Dalton’s Law
Gay-Lussac’s Law Pressure and temperature relationship
Pressure results from molecular collisions Pressure of gas is DIRECTLY proportional to
temperature. P , T P , T
P1 = P2 SOOO T1 = T2
P1T2 = P2T1
Remember to keep units the same. Temperature MUST be in Kelvin
Example 1:
A coke can has 5.00atm of gas at 21°C. Calculate the pressure inside the can when it is found in a warehouse during the summer at 38°C.
Example 2:
The pressure of my tires before a road trip to Wyoming was 1.5atm at 25°C. After returning to North Carolina, my tire pressure is 1.7atm. What is the temperature (in °C) outside?
Example 3:
A gas sample in a closed container with a temperature of 100°C and a pressure of 3.00atm is heated to 300°C. What is the pressure of the gas at this elevated temperature?
Avogadro’s Law
Volume of a gas is DIRECTLY proportional to # of gas particles (moles of gas) Temperature and Pressure are held constant
V1 = V2 n1 = n2 # gas particles, volume # gas particles, volume
Ex. Blowing up a balloon
Dalton’s Law of Partial Pressures
Pressure of each gas DIRECTLY proportional to amount of moles of a gas Increase gas particles, increase pressure Decrease gas particles, decrease pressure
Partial pressure— Pressure of one gas that contributes to the total
pressure in a mixture of gases Total mixture pressure----
The sum of the individual gas pressures in a mixture
Dalton’s Law of Partial Pressures
Total Pressure (PT) of gas mixture = Sum of partial pressures of each gas in the
mixture
PT = P1 + P2 + P3
Example 1:
Calculate the partial pressure (in mmHg) exerted by the 4 main gases in air at 760 mmHg: nitrogen, oxygen, argon, and carbon dioxide. Their abundance by volume is 78.08%, 20.95%, 0.934%, and 0.035% respectively.
Water Displacement with Dalton’s Law
How do we collect and measure gases? Water displacement
Gas displaces water but the gas is mixed with water vapor
Application of Dalton’s Law allows the adjustment for the amount of water vapor to be made so just the amount of gas collected can be measured.
Water Displacement with Dalton’s Law
(cont.) Water vapor is mixed in with gas of interest
so need to separate.
PT = Pgas + Pwater
look up vapor pressure of water at different temperatures
Example 2:
A sample of nitrogen gas is collected over water at a temperature of 23.0°C. What is the pressure of the nitrogen gas if atmospheric pressure is 785 mmHg?
Example 3:
A student has stored 100.0 ml of neon gas over water on a day when the temperature was 27.0°C. If the barometer in the room reads 743.3 mmHg, what is the pressure of the neon gas in the container?
Homework
Read over lab procedure
Recommended