7. Gases

Standard Temperature and Pressure

STP Gas Chemistry (Standard Temperature and Pressure) Examples Practice Problems Questions Shortcut

Suppose you have two 1-L flasks, one containing N2 at STP,
the other containing CH4 at STP. How do these systems compare
with respect to (a) number of molecules?

Propane gas 1C3H82 is often used as fuel in rural areas. How many liters of CO2 are formed at STP by the complete combustion of the propane in a container with a volume of 15.0 L and a pressure of 4.50 atm at 25.0 °C? The equation for the combustion of propane is: 
C3H81g2 + 5 O21g2¡3 CO21g2 + 4 H2O1l2
(LO 10.4, 10.5)
(a) 61.8 L (b) 186 L
(c) 20.6 L (d) 2.21 * 103 L

A gaseous hydrogen- and carbon-containing compound is
decomposed
and found to contain 85.63% C and 14.37% H by
mass. The mass of 258 mL of the gas, measured at STP, was
0.646 g. What is the molecular formula of the compound?

At standard temperature and pressure, the molar volumes of Cl2 and NH3 gases are 22.06 and 22.40 L, respectively. (c) The densities of crystalline Cl2 and NH3 at 160 K are 2.02 and 0.84 g/cm3, respectively. Calculate their molar volumes.

One mole of an ideal gas has a volume of 22.414 L at STP. 
Assuming ideal behavior, what are the densities of the following 
gases in g/L at STP? 
(a) CH4 (b) CO2 (c) O2

Lithium reacts with nitrogen gas according to the reaction:
6 Li(s) + N2( g)¡2 Li3N(s)
What mass of lithium (in g) reacts completely with 58.5 mL of
N2 gas at STP?

What Are Standard Conditions?

Titanium(III) chloride, a substance used in catalysts for preparing 
polyethylene, is made by high-temperature reaction 
of TiCl4 vapor with H2: 
2 TiCl41g2 + H21g2¡2 TiCl31s2 + 2 HCl1g2 
(b) How many liters of HCl gas at STP will result from the 
reaction described in part (a)?

Automobile air bags inflate following a serious impact. The impact
triggers the chemical reaction:
2 NaN3(s)¡2 Na(s) + 3 N2( g)
If an automobile air bag has a volume of 11.8 L, what mass of
NaN3 (in g) is required to fully inflate the air bag upon impact?
Assume STP conditions.

Standard Temperature and Pressure Example 1

A sample of dichloromethane gas (CH2Cl2) occupies 32.6 L at 310 K and 5.30 atm. Determine its volume at STP?

(b) What is the molar volume of an ideal gas at 
STP?

Chlorine is widely used to purify municipal water supplies 
and to treat swimming pool waters. Suppose that the volume 
of a particular sample of Cl2 gas is 8.70 L at 119.3 kPa 
and 24 °C. (b) What volume will the Cl2 occupy at STP?

The Earth’s atmosphere has a mass of approximately 5.15 * 
1015 kg. If the average molar mass of air is 28.8 g/mol, 
how many moles of gas make up the atmosphere? What 
is the volume of the atmosphere in liters under conditions 
of STP? (Note: The average molar mass of air is the 
weighted average of the molar mass of nitrogen and oxygen. 
0.20132.0 g>mol2 + 0.80128.0 g>mol2 = 28.8 g>mol.)

Many gases are shipped in high-pressure containers. Consider
a steel tank whose volume is 210.0 L that contains O2
gas at a pressure of 16,500 kPa at 23 °C. (b) What volume would the gas occupy at STP?

Use the molar volume of a gas at STP to calculate the density (in
g>L) of nitrogen gas at STP.

Consider the reaction:
2 SO2( g) + O2( g)¡2 SO3( g)
a. If 285.5 mL of SO2 reacts with 158.9 mL of O2 (both
measured at 315 K and 50.0 mmHg), what is the limiting
reactant and the theoretical yield of SO3?

Hydrogen gas (a potential future fuel) can be formed by the reaction
of methane with water according to the equation:
CH4( g) + H2O( g)¡CO( g) + 3 H2( g)
In a particular reaction, 25.5 L of methane gas (measured at a
pressure of 732 torr and a temperature of 25 °C) mixes with
22.8 L of water vapor (measured at a pressure of 702 torr and a
temperature of 125 °C). The reaction produces 26.2 L of hydrogen
gas at STP. What is the percent yield of the reaction?

Which gas sample has the greatest volume at STP?

What are the molecular weights of the gases with the following
densities:
(a) 1.342 g/L at STP

Pressure, Volume and Temperature Relationships - Chemistry Tutorial

Which sample contains more molecules: 1.00 L of O2 at STP, 
1.00 L of air at STP, or 1.00 L of H2 at STP?

A compressed air tank carried by scuba divers has a volume 
of 8.0 L and a pressure of 140 atm at 20 °C. What is the 
volume of air in the tank in liters at STP?

Standard Temperature and Pressure Example 2

An herbicide is found to contain only C, H, N, and Cl. 
The complete combustion of a 100.0-mg sample of the 
herbicide in excess oxygen produces 83.16 mL of CO2 and 
73.30 mL of H2O vapor expressed at STP. A separate analysis 
shows that the sample also contains 16.44 mg of Cl. 
(b) Calculate its empirical formula.

The surface temperature of Venus is about 1050 K, and the pressure is about 75 Earth atmospheres. Assuming that these conditions represent a Venusian “STP,” what is the standard
molar volume in liters of a gas on Venus?

Nitrogen and hydrogen combine to form ammonia via the following reaction: &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 1 N2 (s) &nbsp;+ &nbsp;3 H2 (g) → 2 NH3 (g) What mass of nitrogen is required to completely react with 800.0 mL H2&nbsp;at STP?

At standard temperature and pressure, the molar volumes of Cl2 and NH3 gases are 22.06 and 22.40 L, respectively. (b) On cooling to 160 K, both substances form crystalline solids. Do you expect the molar volumes to decrease or increase on cooling the gases to 160 K?

Imagine that you have two identical flasks, one containing 
hydrogen at STP and the other containing oxygen at STP. 
How can you tell which is which without opening them?

Standard Temperature and Pressure Conversions

Isooctane, C8H18, is the component of gasoline from which 
the term octane rating derives. 
(d) How many moles of air are necessary for the combustion 
of 1 mol of isooctane, assuming that air is 21.0% O2 by 
volume? What is the volume in liters of this air at STP?

Suppose you have two 1-L flasks, one containing N2 at STP, 
the other containing CH4 at STP. How do these systems compare 
with respect to (b) density?

What is STP?

Use the molar volume of a gas at STP to determine the volume
(in L) occupied by 33.6 g of neon at STP.

What is the standard temperature and pressure STP?

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[BOOK CHEM] Clutch Version

Partial Pressure

Partial Pressure (PGas) is the pressure exerted by an individual gas within a container.

Velocity Distributions

Velocity Distributions represent probability distributions for a gas when examining their molar mass and temperature.

Mole Fraction

Mole Fraction (X) represents the mole component by total moles.&nbsp;

Mole Fraction -

The Ideal Gas Law Derivations

The&nbsp;Ideal Gas Law Derivations are a convenient way to solve gas calculations involving 2 sets of the same variables.&nbsp;

Root Mean Square Speed

Root Mean Square Speed&nbsp;allows for the determination of the velocity of 1 type of gas molecule.

The Ideal Gas Law: Density

Under certain conditions of pressure and temperature, the Ideal Gas Law can determine the density&nbsp;of a gas.&nbsp;

Effusion

Effusion is the escaping of gas molecules or atoms through a pinhole.&nbsp;

Kinetic Energy of Gases

Kinetic Energy is the energy an object possesses due to its motion.

Gas Stoichiometry

Gas Stoichiometry involves chemical reactions that contain gases.

The Ideal Gas Law

The Ideal Gas Law formula relates the behavior of gases under varying conditions of pressure, volume, moles and temperature.

Chemistry Gas Laws: Combined Gas Law

The Combined Gas Law&nbsp;is created from “combining” Boyle’s Law, Charles’ Law, and Gay–Lussac’s Law.

Pressure Units

Pressure is the force that is exerted within a given volume of space.&nbsp;

Kinetic Molecular Theory

A gas is seen as a collection of molecules or individual atoms that are in constant motion. The Kinetic-Molecular Theory tries to use data of real gases to predict how an ideal gas would behave if they existed.&nbsp;&nbsp;

In order to accurately study the effect that changes in pressure, temperature and moles have on volume, chemists will often run their experiments under Standard Temperature and Pressure.&nbsp;

The Ideal Gas Law Applications

The Ideal Gas Law Applications establish both the direct and inverse relationships between the Ideal Gas Law variables.

Maxwell-Boltzmann Distribution

The Maxwell-Boltzmann Distribution is a probability distribution curve that describes the speed of a gas at a specific temperature.

Chemistry Gas Laws

Chemistry Gas Laws&nbsp;are laws that relate together the pressure, volume and temperature of a gas.

The Ideal Gas Law: Molar Mass

The Ideal Gas Law can be further extended to find the molar mass of a gas.&nbsp;

Van der Waals Equation

The&nbsp;Van der Waals Equation is used when dealing with real, non-ideal gases.&nbsp;