Question 1

Ideal gas law: For a fixed amount of gas, if the absolute temperature of the gas is doubled, what happens to the pressure of the gas?

Accepted Answer

A

Question 2

Quantity of heat: It is a well-known fact that water has a higher specific heat than iron. Now, consider equal masses of water and iron that are initially in thermal equilibrium. The same amount of heat, 30 calories, is added to each one. Which statement is true?

Accepted Answer

Since water has a higher specific heat than iron, it requires more heat to change its temperature by the same amount. Therefore, when the same amount of heat is added to both, the iron, with its lower specific heat, will experience a greater temperature increase, making it warmer than the water.

Question 3

Thermal expansion: If the temperature of an iron sphere is increased,

Accepted Answer

When the temperature of an iron sphere is increased, its volume increases due to thermal expansion. Since density is mass per unit volume and the mass remains constant while the volume increases, the density of the sphere decreases.

Question 4

Thermal expansion: Two steel spheres are made of the same material and have the same diameter, but one is solid and the other is hollow. If their temperature is increased by the same amount,

Accepted Answer

Thermal expansion affects materials uniformly regardless of their mass distribution for a given shape and material. Both spheres, being of the same material and initially the same size, will expand equally with temperature, maintaining their size equality.

Question 5

Ideal gas law: The number of molecules in one mole of a substance

Accepted Answer

The number of molecules in one mole of any substance is always the same, regardless of the substance's molecular weight, atomic weight, density, or temperature. This number is known as Avogadro's number, which is approximately $6.022 \times 10^{23}$ molecules per mole.

Question 6

Molecular speeds: A sample of an ideal gas is slowly compressed to one-half its original volume with no change in pressure. If the original root-mean-square speed (thermal speed) of the gas molecules was V, the new speed is

Accepted Answer

The answer of Molecular speeds: A sample of an ideal...

Question 7

Molecular speeds: A container is filled with a mixture of helium (light molecules) and oxygen (heavy molecules) gases. A thermometer in the container reads 22°C. Which gas molecules have the greater average kinetic energy?

Accepted Answer

The average kinetic energy of gas molecules in a mixture is determined by the temperature of the system, not by the mass or molecular structure of the gases. Since both helium and oxygen gases are at the same temperature (22°C), they have the same average kinetic energy.

Question 8

Molecular speeds: A sample of an ideal gas is slowly compressed to one-half its original volume with no change in temperature. What happens to the average speed of the molecules in the sample?

Accepted Answer

Since the temperature remains constant and the gas is ideal, the average kinetic energy of the molecules remains constant. Therefore, the average speed of the molecules will also remain constant.

Question 9

Molecular speeds: If we double the root-mean-square speed (thermal speed) of the molecules of a gas, then

Accepted Answer

The answer of Molecular speeds: If we double the root-mean-square...

Question 10

Phase changes: A chunk of ice (T = -20°C) is added to a thermally insulated container of cold water (T = 0°C). What happens in the container?

Accepted Answer

When a chunk of ice at -20°C is added to water at 0°C, heat flows from the warmer water to the colder ice. This causes some of the water to freeze, adding to the ice mass, until thermal equilibrium is reached.

Question 11

Molecular speeds: The average molecular kinetic energy of a gas can be determined by knowing

Accepted Answer

The average molecular kinetic energy of a gas is directly proportional to its temperature. Therefore, only the temperature of the gas needs to be known to determine this quantity. Choice D is the correct answer.

Question 12

Molecular speeds: If the temperature of a fixed amount of an ideal gas is increased, it NECESSARILY follows that

Accepted Answer

When the temperature of a fixed amount of an ideal gas is increased, the kinetic energy of the gas molecules also increases. This leads to an increase in the average speed of the gas molecules, as described by the Maxwell-Boltzmann distribution. The pressure and volume of the gas may change as a result of this increase in temperature, but this is not necessarily true in all situations. Therefore, choice C is the best answer.

Question 13

Molecular speeds: A mole of oxygen (O₂) molecules and a mole of carbon dioxide (CO₂) molecules at the same temperature and pressure have

Accepted Answer

At the same temperature and pressure, a mole of any gas contains the same number of molecules, according to Avogadro's law.

Question 14

Phase changes: When a solid melts,

Accepted Answer

When a solid melts, it absorbs heat energy from the surroundings, causing the temperature of the substance to remain constant until all the solid has melted. Therefore, heat energy enters the substance during the phase change from solid to liquid.

Question 15

Ideal gas law: Which contains more moles of material: 80 grams of helium gas (He, having atomic weight 4.0 g/mol) or 400 grams of argon gas (Ar, having atomic weight 40 g/mol)?

Accepted Answer

The number of moles of a gas can be calculated using the ideal gas law: PV=nRT, where P is pressure, V is volume, n is the number of moles, R is the molar gas constant, and T is temperature. Since both gases are at the same temperature and pressure, we can use the equation to calculate the number of moles of each gas.

For helium: 
n = (m/M) = (80 g)/(4.0 g/mol) = 20 mol

For argon: 
n = (m/M) = (400 g)/(40 g/mol) = 10 mol

Therefore, 80 grams of helium contains more moles of material compared to 400 grams of argon.

Question 16

Thermal expansion: A machinist needs to remove a tight fitting pin of material A from a hole in a block made of material B. The machinist heats both the pin and the block to the same high temperature and removes the pin easily. What statement relates the coefficient of thermal expansion of material A to that of material B?

Accepted Answer

Material B must have a greater coefficient of thermal expansion than material A for the hole to expand more than the pin upon heating, making it easier to remove the pin.

Question 17

Phase changes: When a vapor condenses,

Accepted Answer

During condensation, a vapor turns into a liquid, which is an exothermic process. This means heat energy is released from the substance into the surroundings, hence option C is correct.

Question 18

Ideal gas law: A fixed amount of ideal gas is held in a rigid container that expands negligibly when heated. At 20°C the gas pressure is p. If we add enough heat to increase the temperature from 20°C to 40°C, the pressure will be

Accepted Answer

The pressure of an ideal gas is directly proportional to its temperature (in Kelvin) when the volume and the amount of gas are constant. Increasing the temperature from 20°C (293K) to 40°C (313K) does not double the temperature, so the pressure will increase but will not double, making it less than 2p.

Question 19

Quantity of heat: A thermally isolated system is made up of a hot piece of aluminum and a cold piece of copper; the aluminum and the copper are in thermal contact. The specific heat of aluminum is more than double that of copper. Which object experiences the greater temperature change during the time the system takes to reach thermal equilibrium?

Accepted Answer

The answer of Quantity of heat: A thermally isolated system...

Question 20

Conduction of heat: An architect is interested in estimating the heat loss (in kcal/s) through a sheet of insulating material as a function of the thickness of the sheet. Assuming fixed temperatures on the two faces of the sheet, which one of the graphs in the figure best represents the rate of heat transfer as a function of the thickness of the insulating sheet?

Accepted Answer

The answer of Conduction of heat: An architect is interested...

Quiz 16: Sound and Hearing

Ideal gas law: For a fixed amount of gas, if the absolute temperature of the gas is doubled, what happens to the pressure of the gas?

Quantity of heat: It is a well-known fact that water has a higher specific heat than iron. Now, consider equal masses of water and iron that are initially in thermal equilibrium. The same amount of heat, 30 calories, is added to each one. Which statement is true?

Thermal expansion: If the temperature of an iron sphere is increased,

Thermal expansion: Two steel spheres are made of the same material and have the same diameter, but one is solid and the other is hollow. If their temperature is increased by the same amount,

Ideal gas law: The number of molecules in one mole of a substance

Molecular speeds: A sample of an ideal gas is slowly compressed to one-half its original volume with no change in pressure. If the original root-mean-square speed (thermal speed) of the gas molecules was V, the new speed is

Molecular speeds: A container is filled with a mixture of helium (light molecules) and oxygen (heavy molecules) gases. A thermometer in the container reads 22°C. Which gas molecules have the greater average kinetic energy?

Molecular speeds: A sample of an ideal gas is slowly compressed to one-half its original volume with no change in temperature. What happens to the average speed of the molecules in the sample?

Molecular speeds: If we double the root-mean-square speed (thermal speed) of the molecules of a gas, then

Phase changes: A chunk of ice (T = -20°C) is added to a thermally insulated container of cold water (T = 0°C) . What happens in the container?

Molecular speeds: The average molecular kinetic energy of a gas can be determined by knowing

Molecular speeds: If the temperature of a fixed amount of an ideal gas is increased, it NECESSARILY follows that

Molecular speeds: A mole of oxygen (O₂) molecules and a mole of carbon dioxide (CO₂) molecules at the same temperature and pressure have

Phase changes: When a solid melts,

Ideal gas law: Which contains more moles of material: 80 grams of helium gas (He, having atomic weight 4.0 g/mol) or 400 grams of argon gas (Ar, having atomic weight 40 g/mol) ?

Phase changes: When a vapor condenses,

Ideal gas law: A fixed amount of ideal gas is held in a rigid container that expands negligibly when heated. At 20°C the gas pressure is p. If we add enough heat to increase the temperature from 20°C to 40°C, the pressure will be

Quiz 16: Sound and Hearing

Ideal gas law: For a fixed amount of gas, if the absolute temperature of the gas is doubled, what happens to the pressure of the gas?

Quantity of heat: It is a well-known fact that water has a higher specific heat than iron. Now, consider equal masses of water and iron that are initially in thermal equilibrium. The same amount of heat, 30 calories, is added to each one. Which statement is true?

Thermal expansion: If the temperature of an iron sphere is increased,

Thermal expansion: Two steel spheres are made of the same material and have the same diameter, but one is solid and the other is hollow. If their temperature is increased by the same amount,

Ideal gas law: The number of molecules in one mole of a substance

Molecular speeds: A sample of an ideal gas is slowly compressed to one-half its original volume with no change in pressure. If the original root-mean-square speed (thermal speed) of the gas molecules was V, the new speed is

Molecular speeds: A container is filled with a mixture of helium (light molecules) and oxygen (heavy molecules) gases. A thermometer in the container reads 22°C. Which gas molecules have the greater average kinetic energy?

Molecular speeds: A sample of an ideal gas is slowly compressed to one-half its original volume with no change in temperature. What happens to the average speed of the molecules in the sample?

Molecular speeds: If we double the root-mean-square speed (thermal speed) of the molecules of a gas, then

Phase changes: A chunk of ice (T = -20°C) is added to a thermally insulated container of cold water (T = 0°C) . What happens in the container?

Molecular speeds: The average molecular kinetic energy of a gas can be determined by knowing

Molecular speeds: If the temperature of a fixed amount of an ideal gas is increased, it NECESSARILY follows that

Molecular speeds: A mole of oxygen (O2) molecules and a mole of carbon dioxide (CO2) molecules at the same temperature and pressure have

Phase changes: When a solid melts,

Ideal gas law: Which contains more moles of material: 80 grams of helium gas (He, having atomic weight 4.0 g/mol) or 400 grams of argon gas (Ar, having atomic weight 40 g/mol) ?

Phase changes: When a vapor condenses,

Ideal gas law: A fixed amount of ideal gas is held in a rigid container that expands negligibly when heated. At 20°C the gas pressure is p. If we add enough heat to increase the temperature from 20°C to 40°C, the pressure will be

Molecular speeds: A mole of oxygen (O₂) molecules and a mole of carbon dioxide (CO₂) molecules at the same temperature and pressure have