Chapter 20: The Micro/Macro Connection

Solids and liquids resist being compressed. They are not totally incompressible, but it takes large forces to compress them even slightly. If it is true that matter consists of atoms, what can you infer about the microscopic nature of solids and liquids from their incompressibility?

The number density of an ideal gas at STP is called the Loschmidt number. Calculate the Loschmidt number.

FIGURE EX20.10 is a histogram showing the speeds of the molecules in a very small gas. What are

(a) the most probable speed,

(b) the average speed, and

(c) the rms speed?

The number density in a container of neon gas is $5.00\times {10}^{25}{m}^{-3}$. The atoms are moving with an rms speed of $660m/s$. What are

(a) the temperature and

(b) the pressure inside the container?

At $100°C$ the rms speed of nitrogen molecules is $576m/s$. Nitrogen at $100°C$ and a pressure of $2.0atm$ is held in a container with a $10cm\times 10cm$ square wall. Estimate the rate of molecular collisions (collisions/s) on this wall.

A cylinder contains gas at a pressure of $2.0atm$and a number density of$4.2\times {10}^{25}{m}^{-3}$. The rms speed of the atoms is $660m/s$. Identify the gas.

A gas consists of a mixture of neon and argon. The $rms$speed of the neon atoms is $400m/s$. What is the $rms$ speed of the argon atoms?

What are the $rms$ speeds of (a)argon atoms and (b) hydrogen molecules at $800°C$ ?

$1.5m/s$is a typical walking speed. At what temperature $(in°C)$would nitrogen molecules have an $rms$ speed of$1.5m/s$ ?

At what temperature $(in°C)$do hydrogen molecules have the same $rms$ speed as nitrogen molecules at $100°C$ ?