7. Gases

The Ideal Gas Law: Molar Mass

Practice Problem: Molar Mass of a Gas

The Ideal Gas Law: Molar Mass Example 1

Gaseous compound Q contains only xenon and oxygen.
When 0.100 g of Q is placed in a 50.0-mL steel vessel at
0 °C the pressure is 0.229 atm.
(a) What is the molar mass of Q, and what is a likely
formula?

The mass of an evacuated 255 mL flask is 143.187 g. The mass of
the flask filled with 267 torr of an unknown gas at 25 °C is
143.289 g. Calculate the molar mass of the unknown gas.

The Ideal Gas Law: Molar Mass Example 2

The molar mass of a volatile substance was determined by
the Dumas-bulb method described in Exercise 10.53. The
unknown vapor had a mass of 2.55 g; the volume of the
bulb was 500 mL, pressure 101.33 kPa, and temperature
37 °C.Calculate the molar mass of the unknown vapor.

Suppose you are given two flasks at the same temperature,
one of volume 2 L and the other of volume 3 L. The 2-L flask
contains 4.8 g of gas, and the gas pressure is x kPa. The 3-L
flask contains 0.36 g of gas, and the gas pressure is 0.1x. Do
the two gases have the same molar mass? If not, which contains
the gas of higher molar mass?

Solve the ideal gas law for n: n = (PV)/(RT) and then use the definition of molar mass: Molar Mass = mass(m)/moles(n)

Remember that n = mass/(Molar Mass). Substitute into the ideal gas law to solve for molar mass.

 Calculate the molar mass for 2.50 g of an unknown gas in a 0.500-L container at a pressure of 735 mmHg and a temperature of 22&#x2103;. 

What is the molecular formula of a compound that contains 39.0% carbon, 16.0% hydrogen, and 45.0% nitrogen, if 0.1576 g of the compound occupies 125 mL with a pressure of 0.9820 atm at 295.15 K?

A gaseous hydrogen- and carbon-containing compound is decomposed
and found to contain 82.66% carbon and 17.34% hydrogen
by mass. The mass of 158 mL of the gas, measured at 556
mmHg and 25 °C, was 0.275 g. What is the molecular formula
of the compound?

Find molar mass of an unknown gas with ideal gas equation

How to Find Gas Density and Molar Mass at STP (Standard Temperature and Pressure) Example, Shortcut

Cyclopropane, a gas used with oxygen as a general anesthetic,
is composed of 85.7% C and 14.3% H by mass. 
(a) If 1.56 g of cyclopropane has a volume of 1.00 L at 99.7
kPa and 50.0 °C, what is the molecular formula of cyclopropane?

A 248-mL gas sample has a mass of 0.433 g at a pressure of
745 mmHg and a temperature of 28 °C. What is the molar mass
of the gas?

What volume is occupied by 0.118 mol of helium gas at a pressure
of 0.97 atm and a temperature of 305 K? Would the volume
be different if the gas was argon (under the same conditions)?

A sample of gas has a mass of 38.8 mg. Its volume is 224 mL at a
temperature of 55 °C and a pressure of 886 torr. Find the molar
mass of the gas.

Combustion analysis of 0.1500 g of methyl tert-butyl ether, an octane booster used in gasoline, gave 0.3744 g of CO2 and 0.1838 g of H2O. When a flask having a volume of 1.00 L was evacuated and then filled with methyl tertbutyl ether vapor at a pressure of 100.0 kPa and a temperature of 54.8 °C, the mass of the flask increased by 3.233 g.

(b) What is the molecular weight and molecular formula of methyl tert-butyl ether?

To identify a homonuclear diatomic gas, a chemist weighted an evacuated flask with a volume of 3.9 L then filled it with the gas at a pressure of 2.00 atm and 29.0 ºC. The chemist then re-weighted the flask and recorded the difference in mass as 8.81 g. Identify the gas.a) H2b) N2c) Cl2d) F2e) O2

Avogadro's Law - Volume and Moles

A sample of gas has a mass of 0.555 g. Its volume is 117 mL at a
temperature of 85 °C and a pressure of 753 mmHg. Find the
molar mass of the gas.

Applications of the Ideal Gas Law:  Molar Mass of a Gas

In the Dumas-bulb technique for determining the molar
mass of an unknown liquid, you vaporize the sample of a
liquid that boils below 100 °C in a boiling-water bath and
determine the mass of vapor required to fill the bulb. From
the following data, calculate the molar mass of the unknown
liquid: mass of unknown vapor, 1.012 g; volume of bulb,
354 cm3; pressure, 98.93 kPa; temperature, 99 °C.

A 113-mL gas sample has a mass of 0.171 g at a pressure of
721 mmHg and a temperature of 32 °C. What is the molar mass
of the gas?

The Ideal Gas Law and Molar Mass and Density of a Gas

(b) Calculate the molar mass of a gas if
2.70 g occupies 0.97 L at 134.7 Pa and 100 °C.

Suppose you are given two 2-L flasks and told that one contains
a gas of molar mass 28, the other a gas of molar mass 56,
both at the same temperature and pressure. The mass of gas in
the flask A is 1.0 g and the mass of gas in the flask B is 2.0 g.
Which flask contains the gas of molar mass 28, and which
contains the gas of molar mass 56?

Rearrangement of the Ideal Gas Law:  Molar Mass and Density

Learn the toughest concepts covered in Chemistry with step-by-step video tutorials and practice problems by world-class tutors

Jules

General Chemistry

https://static.studychannel.pearsonprd.tech/courses/general-chemistry/thumbnails/general-chemistry

#FFFFFF

Pathways to Chemistry

Ben's Chem Videos

Chemin10

WinElements

Jules Bruno

Professor Dave Explains

Conquer Chemistry

1. Intro to General Chemistry

2. Atoms & Elements

3. Chemical Reactions

4. BONUS: Lab Techniques and Procedures

5. BONUS: Mathematical Operations and Functions

6. Chemical Quantities & Aqueous Reactions

8. Thermochemistry

9. Quantum Mechanics

10. Periodic Properties of the Elements

11. Bonding & Molecular Structure

12. Molecular Shapes & Valence Bond Theory

13. Liquids, Solids & Intermolecular Forces

14. Solutions

15. Chemical Kinetics

16. Chemical Equilibrium

17. Acid and Base Equilibrium

18. Aqueous Equilibrium

19. Chemical Thermodynamics

20. Electrochemistry

21. Nuclear Chemistry

22. Organic Chemistry

23. Chemistry of the Nonmetals

24. Transition Metals and Coordination Compounds

[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;

Standard Temperature and Pressure

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 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;