A hollow container is filled with an ideal gas. The container is designed to maintain a constant pressure by allowing gas to enter or leave as needed. At all times the gas & container are in thermal equilibrium. Initially the temperature is 2350 K. Then the temperature decreases to 500 K and the volume decreases to 0.81 times the initial volume. Determine the coefficient of volume expansion for the container and the ratio of the final number of moles to the initial number of moles. Bcontainer nf ni = = K-1

(a) An ideal gas occupies a volume of 1.0 cm3 at 20.C and atmospheric pressure. Determine the number of molecules of gas in the container, (b) If the pressure of the 1.0-cm3 volume is reduced to 1.0 1011 Pa (an extremely good vacuum) while the temperature remains constant, how many moles of gas remain in the container?

Consider a gas filling two connected chambers that are separated by a removable barrier (Fig. P20.68). The gas molecules on the left (red) are initially at a higher temperature than the ones on the right (blue). When the barrier between the two chambers is removed, the molecules begin to mix and move from one chamber to the other. a. Describe what happens to the temperature in the left chamber and in the right chamber as time goes on, once the barrier is open. Discuss in terms of the mixing of the molecules from each gas. b. Describe what happens to the most probable speed and average speed in the left chamber and in the right chamber as time goes on, once the barrier is open. Do they increase or decrease by the same factor? Explain. FIGURE P20.68 Problems 68 and 69.

In the text, it was shown that N/V=2.681025m3 for gas at STP. (a) Show that this quantity is equivalent to N/V=2.681019cm3, as stated. (b) About how many atoms are mere in one m3 (a cubic micrometer) at STP? (c) What does your answer to part (b) imply about the separation of Mama and molecules?