7. Gases

Kinetic Molecular Theory

Kinetic Molecular Theory and its Postulates

What are the basic assumptions of the kinetic–molecular 
theory?

The Kinetic Molecular Theory (Animation)

Kinetic Theory and Temperature

Which of the following statements best explains why a closed
balloon filled with helium gas rises in air?
(a) Helium is a monatomic gas, whereas nearly all the molecules
that make up air, such as nitrogen and oxygen, are
diatomic.
(b) The average speed of helium atoms is greater than the
average speed of air molecules, and the greater speed
of collisions with the balloon walls propels the balloon
upward.
(c) Because the helium atoms are of lower mass than the average
air molecule, the helium gas is less dense than air.
The mass of the balloon is thus less than the mass of the
air displaced by its volume.
(d) Because helium has a lower molar mass than the average
air molecule, the helium atoms are in faster motion. This
means that the temperature of the helium is greater than
the air temperature. Hot gases tend to rise.

The temperature of a 5.00-L container of N2 gas is increased
from 20 °C to 250 °C. If the volume is held constant,
predict qualitatively how this change affects the following:
(a) the average kinetic energy of the molecules.

Identify the true statement about deviations from ideal gas 
behavior. (LO 10.12) 
(a) The attractive forces between gas particles cause the true 
volume of the sample to be larger than predicted by the 
ideal gas law. 
(b) The attractive forces between gas particles most influence 
the volume of a sample at low pressure. 
(c) The volume of the gas particles themselves most influences 
the volume of the sample at low pressure. 
(d) The volume of the gas particles themselves causes the 
true volume of the sample to be larger than predicted by 
the ideal gas law.

Which postulate of the kinetic molecular theory breaks down
under conditions of high pressure? Explain.

Kinetic Molecular Theory Example 1

Kinetic Theory of Gases

The Kinetic Molecular Theory of Gas (part 2)

(c) What happens to a gas if you put it under extremely high pressure?

The phase diagram for SO2 is shown here.
(d) At which of the three points marked in red
does SO21g2 most closely approach ideal-gas behavior?
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/7d4b8d652b5ee54f-1665420901663.jpg" alt="" />

Two 112-L tanks are filled with gas at 330 K. One contains
5.00 mol of Kr, and the other contains 5.00 mol of O2.
Considering the assumptions of kinetic–molecular theory,
rank the gases from low to high for each of the following
properties.
(a) Collision frequency

The planet Jupiter has a surface temperature of 140 K and a
mass 318 times that of Earth. Mercury (the planet) has a surface
temperature between 600 K and 700 K and a mass 0.05
times that of Earth. On which planet is the atmosphere
more likely to obey the ideal-gas law? Explain.

(b) List two reasons why the gases deviate from ideal behavior.

Indicate which of the following statements regarding the
kinetic-molecular theory of gases are correct. (a) The average
kinetic energy of a collection of gas molecules at a given temperature
is proportional to m1>2.

The phase diagram for SO2 is shown here.
(e) At which of the three red points does SO21g2 behave
least ideally?
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/d10f3f93f82da398-1674838698316.jpg" alt="" />

At constant pressure, the mean free path 1l2 of a gas molecule
is directly proportional to temperature. At constant
temperature, l is inversely proportional to pressure. If you
compare two different gas molecules at the same temperature
and pressure, l is inversely proportional to the square
of the diameter of the gas molecules. Put these facts together
to create a formula for the mean free path of a gas
molecule with a proportionality constant (call it Rmfp, like
the ideal-gas constant) and define units for Rmfp.

Gases: Kinetic Molecular Theory

At high temperatures the attractive forces between molecules becomes negligible.

At high pressure the volume of gas molecules become significant.

An increase or decrease in the moles of gas causes the gas constant value to change.

Which of the following statements would correctly explain the non-ideal behavior of a gas based on the Kinetic Molecular Theory (KMT)? a) At high temperatures the attractive forces between molecules becomes negligible. b) At high pressure the volume of gas molecules become significant. c) An increase or decrease in the moles of gas causes the gas constant value to change.

At 273 K and 1 atm pressure, 1 mol of an ideal gas occupies 22.4 L. (Section 10.4) (c) In which parts of the atmosphere would you expect gases to behave most ideally (ignoring any photochemical reactions)? [Section 18.1]

Which of the following statements is/are true for gas molecules according to the Kinetic Molecular Theory? I.Increasing the amount of gas molecules increases the pressure by increasing the force of the collisions. II.Decreasing the temperature of a gas decreases the pressure by increasing the force of the collisions. III.Decreasing the volume of a gas increases pressure by increasing the frequency of the collisions.

Two 112-L tanks are filled with gas at 330 K. One contains 
5.00 mol of Kr, and the other contains 5.00 mol of O2. 
Considering the assumptions of kinetic–molecular theory, 
rank the gases from low to high for each of the following 
properties. 
(d) Pressure

Consider the following gases, all at STP: Ne, SF6, N2, CH4.
(a) Which gas is most likely to depart from the assumption
of the kinetic-molecular theory that says there are
no attractive or repulsive forces between molecules?

A Level Physics: Assumptions of the Kinetic Theory of Gases

Determine whether each of the following changes will increase,
decrease, or not affect the rate with which gas molecules
collide with the walls of their container:
(a) increasing the volume of the container
(b) increasing the temperature
(c) increasing the molar mass of the gas

Hydrogen Molecule Bond Formation

Based on the kinetic-molecular theory, which of the following is/are true? I.At a given temperature, all gases have the same average kinetic energy. II.At a given temperature, different gases have the same average velocities. III.The average kinetic energy is proportional to the absolute temperature.

Which of the following statements is false?
(a) Gases are far less dense than liquids.
(b) Gases are far more compressible than liquids.
(c) Because liquid water and liquid carbon tetrachloride do
not mix, neither do their vapors.
(d) The volume occupied by a gas is determined by the volume
of its container.

Kinetic Molecular Theory and the Ideal Gas Laws

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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;

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: 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;