Warm-up•I have an unknown volume of gas held at a temperature of 115 K in a container with a pressure of 60 atm. If by increasing the temperature to 225 K and decreasing the pressure to 30 atm causes the volume of the gas to be 29 liters, how many liters of gas did I start with?
The Ideal Gas LawUnit 8, Day 7Kimrey4 December 2012
A Bit More About Gases•Remember gases are really tiny particles bouncing off of everything.
•These collisions are perfectly elastic. Meaning that no energy is lost as they collide.
•It’s because of this that the combined gas law works (P1V1/T1 = P2V2/T2).
Adding more gas•So what happens if we add more of a gas?
•This can be accounted for by the ideal gas law.
Ideal Gas LawPV=nRT
•P= Pressure•V= Volume•n= moles•R= gas constant•T= Temperature
Units•Temperature must be in Kelvin.•Volume must be in liters (Remember: King Henry Died by drinking chocolate milk)
•Pressure can be in atm, mmHg, or kPa BUT you must use the appropriate R for whatever units of pressure you have.
•R is a constant and can be: (three options are found on the reference tables)
Converting to Kelvin•Temperature can also be measured in a
unit known as Kelvin. ▫Degrees Celsius plus 273 = Temperature in
Kelvin▫You don’t have to remember this! The
reference tables show that 0 °C is the same as 273K
•45°C is what in Kelvin?•5°C is what in Kelvin?
Example•How many moles of a gas at 100°C does it take to fill a 1.00L flask to a pressure of 1.50 atm?
Example•If I have 4 moles of a gas at a pressure of 5.6 atm and a volume of 12 liters, what is the temperature?
Example•If I contain 3 moles of gas in a container with a volume of 60 liters and at a temperature of 400 K, how many atmospheres of pressure are inside the container?
Example•If I have an unknown quantity of N2 held at a temperature of 1195 K in a container with a volume of 25 liters and a pressure of 560 atm, how many grams of N2 do I have?
Warm-up•If I have an unknown quantity of N2 held at a temperature of 1195 K in a container with a volume of 25 liters and a pressure of 560 atm, how many grams of N2 do I have?
Stoichiometry!!Unit 8, Day 7Kimrey4 December 2012
Molar Volume•1 mole = 22.4 L of a gas at STP•STP = 0°C and 1 atm
Examples•How many liters of Nitrogen gas are there in 4.56 moles?
•How many liters of fluorine are there in 56.7 grams?
Stoichiometry…Again!N2 + H2 NH3
•64.0 L of nitrogen will produce how many liters of ammonia (at STP)?
•Don’t forget to balance!!!
Mole - Volume2H2 + O2 2H2O
•How many liters of water will be produced from 15 moles of oxygen?
Mass - Volume2H2 + O2 2H2O
•How many liters of water will be produced from 100 grams of Hydrogen gas if Oxygen gas is in excess?
STP•Standard Temperature and Pressure
•1 atm and 0 °C
Example•In a laboratory experiment, 85.3 moles of a gas are collected at 24 °C and 733 mm Hg pressure. Find the volume at STP.
Not at STP…•Use the ideal gas law to determine volume
•Then use that volume to complete the stoichiometry
ExampleNa3PO4 + 3 KOH 3 NaOH + K3PO4
•If you have 25 moles of KOH at 175 K and 3.4 atm, how many liters of K3PO4 are produced?
ExampleC3H6O + 4 O2 3 CO2 + 3 H2O
•At 823 mmHg and 329 K, 135 moles of oxygen are mixed with excess C3H6O. How many liters of water are produced?
