How does the frequency of collisions of the molecules of a gas with the walls of the container change as the volume of the gas is decreased at constant temperature? Justify your answer on the basis of the kinetic model of gases.

Short Answer

Expert verified
The frequency of collisions of the molecules of a gas with the walls of the container increases as the volume of the gas is decreased at constant temperature, as per the Kinetic Molecular Theory.

Step by step solution

01

Understanding the Kinetic Molecular Theory

According to the Kinetic Molecular Theory, an ideal gas is composed of a large number of small molecules that are in constant random motion. The pressure of the gas is due to collisions between the molecules and the walls of the container. If the temperature remains constant, the average kinetic energy of the gas molecules does not change.
02

Relating Volume and Collision Frequency

When the volume of a gas is decreased at constant temperature, the same number of molecules is contained in a smaller space. This means the molecules are closer together and will collide more frequently with each other and with the walls of the container.
03

Concluding Collision Frequency Change

Since the molecules have less space to travel before hitting a wall, the frequency of collisions with the walls increases as the volume decreases, assuming temperature and number of molecules remain constant.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Collision Frequency
Understanding collision frequency is vital when studying the behavior of gases. Collision frequency refers to the number of times gas molecules collide with the walls of their container per unit time. When examining how a gas's volume affects collision frequency, it's crucial to remember the underlying principle of the Kinetic Molecular Theory: gas molecules are in continuous random motion, and their collisions with the container's walls result in pressure.

As the volume of a gas decreases while maintaining a constant temperature, the molecules are squeezed into a tighter space. There are just as many molecules but less room to move around, causing them to bump into the walls more often. This increased collision frequency elevates the pressure, provided the temperature doesn't change to compensate. Therefore, knowing this relationship helps predict how changes in volume influence the gas pressure, leading to an understanding of gas laws and behavior.
Gas Laws
Gas laws are the cornerstone principles which explain how physical properties of gases change in response to external conditions. These laws synthesize the relationship between pressure (P), volume (V), temperature (T), and amount of gas in moles (n). Boyle's Law, for instance, shows that at constant temperature, the pressure of a gas is inversely proportional to its volume – a concept directly linked to collision frequency.

When the volume is decreased at a constant temperature, Boyle's Law predicts that the pressure will increase due to that higher collision frequency against the container's walls. This law is part of the ideal gas behavior and is one of the key connections between theoretical concepts and real-world gas behavior.
Ideal Gas Behavior
The notion of the ideal gas is used as a model to simplify the understanding of gas behavior. An ideal gas follows the gas laws perfectly and has certain characteristics: the particles have no volume and experience no intermolecular forces. While no gas is truly ideal, many gases behave nearly ideally under a range of conditions.

An important equation to describe ideal gas behavior is the Ideal Gas Law, which is given by PV = nRT, where R is the gas constant. This equation offers a powerful tool to calculate one variable when all other variables are known. It shows how under constant temperature (the T in the equation), changing the volume (V) will affect the pressure (P), assuming the amount of gas (n) remains unchanged.
Constant Temperature Gas Behavior
The behavior of gases at constant temperature is particularly interesting. When a gas's temperature is held steady, the kinetic energy of the molecules remains constant. According to the Kinetic Molecular Theory, this means that any changes in volume or pressure are due to alterations in collision frequency or spatial distribution of molecules.

At constant temperature, increasing the pressure on a gas by reducing its volume does not increase the average kinetic energy of the particles; it merely decreases the space available for the particles to move. As a result, particles collide with the container's walls more frequently, leading to an increased pressure observed as a macroscopic property of the gas.

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Most popular questions from this chapter

Dinitrogen oxide, \(\mathrm{N}_{2} \mathrm{O}\), gas was generated from the thermal decomposition of ammonium nitrate and collected over water. The wet gas occupied \(126 \mathrm{~mL}\) at \(21^{\circ} \mathrm{C}\) when the atmospheric pressure was 755 Torr. What volume would the same amount of \(d r y\) dinitrogen oxide have occupied if collected at 755 Torr and \(21^{\circ} \mathrm{C}\) ? The vapor pressure of water is \(18.65\) Torr at \(21^{\circ} \mathrm{C}\).

What is the density (in \(\mathrm{g} \cdot \mathrm{L}^{-1}\) ) of hydrogen sulfide, \(\mathrm{H}_{2} \mathrm{~S}\), at (a) \(1.00\) atm and \(298 \mathrm{~K}\); (b) \(45.0^{\circ} \mathrm{C}\) and \(0.876\) atm?

(a) A \(125-\mathrm{mL}\) flask contains argon at \(1.30\) atm and \(77^{\circ} \mathrm{C}\). What amount of Ar is present (in moles)? (b) A \(120 .-\mathrm{mL}\) flask contains \(2.7 \mu \mathrm{g}\) of \(\mathrm{O}_{2}\) at \(17^{\circ} \mathrm{C}\). What is the pressure (in Torr)? (c) A 20.0-L flask at \(215 \mathrm{~K}\) and 20. Torr contains nitrogen. What mass of nitrogen is present (in grams)? (d) A 16.7-g sample of krypton exerts a pressure of \(1.00 \times 10^{2} \mathrm{~m}\) Torr at \(44^{\circ} \mathrm{C}\). What is the volume of the container (in liters)? (e) A \(2.6-\mu \mathrm{L}\) ampoule of xenon has a pressure of \(2.00\) Torr at \(15^{\circ} \mathrm{C}\). How many Xe atoms are present?

Determine the ratio of the number of molecules in a gas having a speed ten times as great as the root mean square speed to the number having a speed equal to the root mean square speed. Is this ratio independent of temperature? Explain your reasoning.

A chemist prepares \(0.100 \mathrm{~mol}\) Ne gas at a certain pressure and temperature in an expandable container. Another \(0.010 \mathrm{~mol}\) Ne is then added to the same container. How must the volume be changed to keep the pressure and temperature the same?

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