Honors Chemistry
Name: ___________________________________ Date: _______________ Mods: ______________
10.4 – The Ideal Gas Law
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Gases: Real vs. Ideal
o
We assume that gases behave “_____________________” meaning…
(1) They obey the Gas Law relationships under all temperatures and pressures
(2) They obey all statements listed by KMT (gases have no volume, no attractive forces, etc)
o
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Ideal gases do not actually exist in the real world however, real gases behave almost ideally at
_______________ temperature and _______________ pressure conditions (this is when gas
particles are the fastest moving, furthest apart, & have least interaction)
Ideal Gas Law:
Equation:
Ideal Gas Constant “R”:
Note: Units of volume, pressure, and temperature must match those in the “R” value used
Example Problem: How many moles of air are there in a 3.0 L bottle at 19°C and 747 mm Hg?
10.5 – Further Applications of the Ideal Gas Law
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Given Mass & Molar Mass: Since moles = mass/molar mass…
Ideal Gas Equation Rearranged:
[m = mass (in grams); MM = molar mass (in g/mol)]
Example Problem: An unknown gas with a mass of 2.89 grams at a pressure of 714 torr and a
temperature 36°C takes up a volume of 3.53 L. What is the molar mass of the unknown gas?

Given Density: Since density = mass/volume…
Ideal Gas Equation Rearranged:
[D = density (g/L); MM = molar mass (in g/mol)]
Example Problem: What is the density of carbon tetrachloride vapor pressure at of 714 torr and
125°C?

Using Ideal Gas Law & Gas Stoichiometry: Often, volumes of gases consumed or produced in
chemical reactions need to be calculated…When given a reaction that involves a gas, PV=nRT can
be used to solve for any variable involving the gaseous compound in the reaction only… BUT, we
can use stoichiometry in combination with the ideal gas law to solve for masses or moles of any
compound in a balanced equation
Example Problem: Given the reaction below, how many grams of NaN3 must be decompose if a 36
L airbag in a car is filled up with nitrogen gas at a pressure of 874 mm Hg and a temperature of
26°C?
2 NaN3 (s)  2 Na (s) + 3 N2 (g)
Example Problem: How many liters of NH3 (g) at 850ºC and 5.00 atm are required to react with
1.00 mol of O2 (g) in the reaction below?
4 NH3 (g) + 5 O2 (g)  4 NO (g) + 6 H2O (g)

Using Ideal Gas Law & Gas Stoichiometry @ STP Conditions: Recall that at STP conditions
ONLY, 1 mole of any gas have a molar volume of 22.4 L
Example Problem: Carbon monoxide reacts with oxygen gas to produce gaseous carbon dioxide. If
1.0 L of carbon monoxide reacts with oxygen at STP, how many liters of oxygen are required to
react?
Example Problem: Assume that 5.60 L of hydrogen gas at STP reacts with copper (II) oxide
according to the following balanced equation:
CuO (s) + H2 (g)  Cu (s) + H2O (g)
a. How many moles of H2 react?
c. How many grams of copper metal are produced?
Ideal Gas Law WS #1
1.
How many moles of gas does it take to occupy 120 liters at a pressure of 2.3 atmospheres and a
temperature of 340 K?
2.
If I have a 50 liter container that holds 45 moles of gas at a temperature of 2000 C, what is the
pressure inside the container?
3.
It is not safe to put aerosol canisters in a campfire, because the pressure inside the canisters gets
very high and they can explode. If I have a 1.0 liter canister that holds 2 moles of gas, and the
campfire temperature is 14000 C, what is the pressure inside the canister?
4.
How many moles of gas are in a 30 liter scuba canister if the temperature of the canister is 300 K
and the pressure is 200 atmospheres?
5.
I have a balloon that can hold 100 liters of air. If I blow up this balloon with 3 moles of oxygen gas
at a pressure of 1 atmosphere, what is the temperature of the balloon?
Ideal Gas Law WS #2
1.
If 3.7 moles of propane are at a temperature of 28oC and are under 154.2 kPa of pressure, what
volume does the sample occupy?
2.
A sample of carbon monoxide at 57oC and under 0.67 atm of pressure takes up 85.3 L of space.
What mass of carbon monoxide is present in the sample?
3.
At –45oC, 71 g of fluorine gas take up 6843 mL of space. What is the pressure of the gas, in kPa?
4.
At 971 mm Hg, 145 g of carbon dioxide have a volume of 34.13 dm3. What is the temperature of
the sample, in oC?
5.
At 137oC and under a pressure of 3.11 atm, a 276 g sample of an unknown noble gas occupies
13.46 L of space. What is the identity of the gas?
Gas Stoichiometry WS #1
Directions: Solve the problems using balanced chemical equations and the Ideal Gas Law.
1. Ammonium sulfate, an important fertilizer, can be prepared by the reaction of ammonia with sulfuric
acid according to the following balanced equation:
2 NH3 (g) + H2SO4 → (NH4)2SO4 (aq)
Calculate the volume of NH3 (in liters) needed at 20ºC and 25.0 atm to react with1500 g of H2SO4.
2. If 45.0 L of natural gas, which is essentially methane (CH4), undergoes complete combustion at
730 mm Hg and 20ºC, how many grams of each product in the reaction are formed?
3.
Fritz Haber, a German chemist, discovered a way to synthesize ammonia gas (NH3) by combining
hydrogen and nitrogen gases at extremely high temperatures and pressures.
a. Write the balanced equation for this reaction.
b. If 10 kg of nitrogen gas combines with excess hydrogen gas at 550ºC and 250 atm, what
volume of ammonia gas is produced?
4.
A 3.25 gram sample of solid calcium carbide (CaC2) reacts with water to produce acetylene gas
(C2H2) and aqueous calcium hydroxide. If the gas was captured and measured at 17ºC and 740.0
mm Hg, how many milliliters of acetylene were produced?
5.
Calcium carbonate decomposes at high temperatures to form carbon dioxide and calcium oxide:
CaCO3 (s)  CO2 (g) + CaO(s)
How many grams of calcium carbonate will I need to form 3.45 liters of carbon dioxide at 1.0 atm
and 298 K??
6.
Ethylene burns in oxygen to form carbon dioxide and water vapor:
C2H4 (g) + 3 O2 (g)  2 CO2 (g) + 2 H2O(g)
If the reaction occurs at 31°C and a pressure of 810 mm Hg, how many liters of water vapor can
be formed if 1.25 liters of ethylene are consumed in this reaction?
3)
When chlorine is added to acetylene, 1,1,2,2-tetrachloroethane is formed:
2 Cl2 (g) + C2H2 (g)  C2H2Cl4 (l)
How many liters of chlorine will be needed to make 75.0 grams of C2H2Cl4 at 115.3 kPa and
19.5°C?
Gas Stoichiometry @ STP Conditions WS #2
Directions: Solve the problems using balanced chemical equations. Recall that at STP, 1 mole of
any gas takes up a volume of 22.4 L.
1.
At STP, propane (C3H8) undergoes combustion to produce carbon dioxide and water vapor.
a. How many liters of C3H8 are required to produce 75.0 L of CO2?
b. What volume of H2O is produced?
c. What volume of O2 is required?
2.
Assume that 8.5 L of iodine gas (I2) are produced at STP according to the following balanced
equation:
2 KI (aq) + Cl2 (g)  2 KCl (aq) + I2 (g)
a. How many moles of I2 are produced?
b. How many grams of KI were used?
3.
At STP, solid iron (III) hydroxide decomposes to produce iron (III) oxide and water vapor. If 0.75 L
of water vapor are produced at STP,
a. How many grams of iron (III) hydroxide were used?
b. How many grams of iron (III) oxide were produced?
4.
Solid iron reacts with sulfuric acid (H2SO4) to produce iron (II) sulfate and hydrogen gas. If 650 mL
of hydrogen gas are collected at STP, how many grams of iron (II) sulfate are also produced?
5.
Assume that 13.5 grams of solid aluminum react with HCl according to the following balanced
equation at STP:
2 Al (s) + 6 HCl (aq) → 2 AlCl3 (aq) + 3 H2 (g)
a. How many moles of Al react?
b. How many moles of H2 are produced?
c. How many liters of H2 are produced?