Unit 9: Thermodynamics

A sealed rigid container holds an ideal gas. The gas is heated, and its pressure increases. Which statement best explains the increase in pressure in terms of the atoms?

A gas in a cylinder is at a pressure of 2.4 × 10⁵ Pa. The piston that seals the cylinder has an area of 120 cm². What is the magnitude of the force the gas exerts on the piston?

The absolute temperature of a sample of ideal gas is raised from 300 K to 1200 K. By what factor does the rms speed of its atoms change?

Samples of helium and argon, both ideal monatomic gases, are in thermal equilibrium with each other. The table gives the mass of one atom of each. How do the average kinetic energy and the rms speed of the helium atoms compare with those of the argon atoms?

An atom of mass m moving with speed v strikes a container wall head-on and rebounds elastically, moving straight back. Which expression gives the magnitude of the impulse the wall exerts on the atom?

A sample of an ideal monatomic gas contains N atoms, each of mass m, at pressure P in a container of volume V. Which expression gives the rms speed of the atoms?

A tank of volume 0.020 m³ holds an ideal gas at a pressure of 1.5 × 10⁵ Pa and a temperature of 27 °C. How many moles of gas are in the tank?

A fixed amount of ideal gas is compressed slowly at constant temperature until its volume is one third of its starting volume. How does its final pressure compare with its starting pressure?

A student keeps a fixed amount of gas at constant volume and measures its pressure at several temperatures, as plotted. The data lie on a straight line. Extending the line, at what temperature would the pressure of the gas be zero?

Which statement is part of the classical model of an ideal gas?

Two rigid tanks of equal volume hold ideal gases as described in the table. How does the pressure in tank A compare with the pressure in tank B?

An ideal gas in a container of volume V is at pressure P and absolute temperature T. Which expression gives the number of atoms N in the container?

A student compresses 0.40 mol of an ideal gas slowly in a cylinder kept in a water bath. The table gives the pressure and volume at three moments. What is the temperature of the gas?

A hot metal block is placed in cool water in an insulated container. The graph shows the temperatures of the block and the water against time. Which statement describes the block and the water after about 600 s?

Two samples of gas at different temperatures are separated by a thin metal wall. Which statement best explains, at the level of atoms, why energy is transferred from the hotter sample to the cooler one?

A gas absorbs 500 J of energy by heating while the gas does 200 J of work on its surroundings. What is the change in the internal energy of the gas?

A gas is taken around the cycle A → B → C → D → A shown on the PV diagram. What is the net energy transferred to the gas by heating during one full cycle?

An ideal gas is compressed slowly from state A to state B along the isotherm shown, so its temperature stays constant. During the compression, 660 J of work is done on the gas. Which statement is correct?

A rigid container holds n moles of an ideal monatomic gas. The gas absorbs energy Q by heating, and no work is done on or by the gas. Which expression gives the rise in the gas's temperature?

An ideal monatomic gas has pressure P and volume V. Which expression gives its internal energy?

An ideal gas in a rigid container is heated from state A to state B, as shown on the PV diagram. How does the internal energy of the gas at B compare with its internal energy at A?

Which statement explains why the internal energy of an ideal monatomic gas depends only on its temperature?

A gas in an insulated cylinder is compressed quickly, so no energy is transferred by heating, and its temperature rises. A student says, "The gas was heated." Which response is correct?

How much energy must be transferred to 0.50 kg of water to warm it from 20 °C to 80 °C? The specific heat of water is 4,200 J/(kg·K).

Equal amounts of energy are transferred by heating to samples A and B, which have equal masses. The table gives each sample's temperature rise. How does the specific heat of A compare with that of B?

The table describes two walls of the same material with the same temperature difference across each. How does the rate of energy transfer by conduction through wall 2 compare with that through wall 1?

A 0.25 kg sample of a metal is heated, and its temperature is recorded against the energy transferred to it, as graphed. What is the specific heat of the metal?

On a cold day a metal bench and a wooden bench have both been outside for hours. The table gives their thermal conductivities. Which claim, supported by the table, explains why the metal bench feels colder to sit on?

A slab of material of thermal conductivity k, area A and thickness L has a steady temperature difference ΔT across it. Which expression gives the time needed for energy Q to be conducted through the slab?

Liquid of mass m at temperature T₁ is mixed with liquid of the same kind, of mass 2m, at a lower temperature T₂, in an insulated container. Which expression gives the final temperature?

Blocks of copper and aluminum have equal masses. Each absorbs the same amount of energy by heating. The table gives their specific heats. How does the copper block's temperature rise compare with the aluminum block's?

An isolated system undergoes an irreversible process. What happens to the total entropy of the system?

A gas is taken from state i to state f by path 1 or by path 2, as shown on the PV diagram. How does the change in the entropy of the gas along path 1 compare with that along path 2?