Question 1

Use the following to answer the question: 
-The graph shows the temperature of a 1.0-g sample of material as heat is added to it.The material is initially a solid at 10ºC.The pressure remains constant,and there is no chemical change.The melting point temperature is

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Question 2

Suppose you do 75 kJ of work on a system consisting of 10 kg of water by stirring it with a paddle wheel.During this process,40 kcal of heat is removed.The change in the internal energy of the system is

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Question 3

Use the following to answer the question: 
-The graph shows the temperature of a 1.0-g sample of material as heat is added to it.The material is initially a solid at 10ºC.The pressure remains constant,and there is no chemical change.The specific heat of the liquid phase is

Accepted Answer

Without the graph or specific data points from the graph indicating the temperature change and the amount of heat added to the material in its liquid phase, it's impossible to accurately determine the specific heat of the liquid phase.

Question 4

In a certain thermodynamic process,1000 cal of heat are added to a gas confined in a cylinder.At the same time,1000 J of work are done by the gas as it expands.The increase in internal energy of the gas is

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Question 5

Besides Joule's classic experiment,another way of demonstrating the equivalence between mechanical energy and heat is the following: Put some lead shot into a glass tube,seal both ends of the tube,invert the tube quickly several times,and measure the temperature of the shot.If you assume that all the mechanical energy is converted into heat in the lead shot and that no heat is lost,what is the change in the temperature of the shot if the tube is 1.0 m long,there are 100 g of shot,and the tube is inverted 10 times? (The specific heat of lead is 0.128 kJ/kg · K.)

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Question 6

The first law of thermodynamics has as its basis the same fundamental principle as

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The first law of thermodynamics, also known as the law of conservation of energy, states that energy cannot be created or destroyed, only transferred or converted from one form to another. This is the same fundamental principle as conservation of energy, making B the correct answer.

Question 7

A small water reactor recently installed at Podunk College is operating at the boiling point of water due to the malfunctioning of the cooling system.The operators observe that the water boils away at the rate of 10 L/min.If they assume that all of the reactor energy is absorbed in the water,the power developed by the reactor is approximately

Accepted Answer

We can use the energy balance equation to determine the power developed by the reactor:
Power developed = Mass flow rate x specific heat x change in temperature
We know that 10 L/min of water is boiling away, which is equivalent to a mass flow rate of:
(10 L/min) x (1 kg/L) x (1/60 min/s) = 0.167 kg/s
The specific heat of water is approximately 4.18 kJ/kg-K, and we can assume that the temperature change of the water is from 100°C (boiling point) to 0°C (assuming that the water is being completely boiled away).
Therefore, the power developed by the reactor is:
Power developed = (0.167 kg/s) x (4.18 kJ/kg-K) x (100°C - 0°C)
Power developed = 69.7 kW
Rounding to two significant figures, we get:
Answer: D) 378 kW

Question 8

Use the following to answer the question: 
-The graph shows the temperature of a 1.0-g sample of material as heat is added to it.The material is initially a solid at 10ºC.The pressure remains constant,and there is no chemical change.The specific heat of the solid phase is

Accepted Answer

To determine the specific heat of the solid phase, we need to look at the graph and find the slope of the flat portion of the line corresponding to the solid phase. The slope of the flat portion gives us the specific heat of the solid phase. The flat portion of the line in the graph suggests that the solid phase absorbs heat but does not change its temperature until it reaches the melting point. Thus, the specific heat of the solid phase is the slope of this flat portion of the line, which is given by the formula: specific heat = (heat added) / (mass x temperature change). From the graph, we can see that 20 calories of heat are added to raise the temperature of the solid phase from 10ºC to 25ºC. Therefore, the specific heat of the solid phase is (20 cal) / (1.0 g x 15ºC) = 0.25 cal/g · Cº, which is answer choice B.

Question 9

A 6.0-g lead bullet traveling at 300 m/s penetrates a wooden block and stops.If 50 percent of the initial kinetic energy of the bullet is converted into thermal energy in the bullet,by how much does the bullet's temperature increase? (The specific heat of lead is 128 J/kg · K.)

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Question 10

The first law of thermodynamics is most closely related to

Accepted Answer

The first law of thermodynamics is also known as the law of conservation of energy, which states that energy cannot be created or destroyed, only transferred or converted from one form to another. This directly relates to the conservation of energy.

Question 11

When a substance goes directly from a solid state to a gaseous form,the process is known as

Accepted Answer

The process of converting a solid directly into a gas without going through the intermediate liquid phase is called sublimation. Examples of substances that undergo sublimation include dry ice (solid carbon dioxide), iodine, and camphor. Therefore, option D (sublimation) is the correct answer. Vaporization and evaporization refer to the conversion of a liquid into a gas, while condensation refers to the opposite process of converting a gas into a liquid. Deposition is the opposite of sublimation, i.e., the conversion of a gas directly into a solid.

Question 12

In a certain thermodynamic process,20 cal of heat are removed from a system and 30 cal of work are done on the system.The internal energy of the system

Accepted Answer

The first law of thermodynamics states that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system. In this case, heat is removed (which is equivalent to negative heat being added), and work is done on the system (which can be considered as negative work done by the system). Therefore, the change in internal energy is -20 cal (for the heat removed) - (-30 cal) (for the work done on the system), which equals +10 cal. This means the internal energy increases by 10 cal.

Question 13

Two containers of equal volume are connected by a stopcock as shown below.One container is filled with a gas at a pressure of 1 atm and temperature of 293 K while the other container is evacuated so that it is under vacuum.The containers are thermally isolated from the surrounding so no heat enters or escaped from the system.The stopcock is then opened allowing the gas from one container to fill the other.What is the final temperature of the gas after it has come to equilibrium?

Accepted Answer

Since the containers are thermally isolated, there is no heat transfer between them. Therefore, the total amount of gas and the total volume of the containers remain constant. When the stopcock is opened, the gas from the container with 1 atm pressure expands into the vacuum container until the pressure in both containers is the same. Since the volumes of the containers are equal, the pressure in both containers will be 0.5 atm at equilibrium.

According to the ideal gas law, PV=nRT, where P is the pressure, V is the volume, n is the number of moles of gas, R is the ideal gas constant, and T is the absolute temperature. Since the amount of gas is constant, we can write

P1V1=P2V2

where P1 is the initial pressure, V1 is the initial volume, P2 is the final pressure, and V2 is the final volume.

Substituting the values, we get

1 atm x V = 0.5 atm x V

or V cancels out, and we get P1/2 = 0.5

Therefore, the pressure has decreased by a factor of 2. Using the ideal gas law again, we get

P1V1/nR = P2V2/nR

or T1 = T2

since n and R are constants, and the volumes are the same.

Therefore, the final temperature is the same as the initial temperature, which is 293 K. Thus, the correct answer is C.

Question 14

The percentage of mechanical energy that can theoretically be turned into heat energy according to the first law of thermodynamics is

Accepted Answer

The first law of thermodynamics, also known as the law of energy conservation, states that energy cannot be created or destroyed in an isolated system. This implies that 100% of mechanical energy can theoretically be converted into heat energy, as the total energy in the system remains constant.

Question 15

A state variable is one that allows other variables to be determined using a relationship.Which of the following variables are state variables?

Accepted Answer

Option A lists the three variables that make up the state of a gas - Pressure (P), Volume (V), and Temperature (T). Option B lists Internal Energy (U), which is a state variable as it depends only on the state of the system and not the path taken to get to that state. Option C lists work (W) and heat (Q), which are both path-dependent variables and do not have a fixed value depending on the state of the system. Hence, the best choice(s) are options A and B, making option D the correct answer.

Question 16

How much internal energy is contained in 1 mole of monatomic gas at STP?

Accepted Answer

The answer of How much internal energy is contained in...

Question 17

A system absorbs heat Q and has an equal amount of positive work done on it.What is the change in the internal energy of the system?

Accepted Answer

According to the first law of thermodynamics, the change in internal energy (ΔU) is given by ΔU = Q - W. Since the work done on the system is equal to Q, ΔU = Q - (-Q) = Q + Q = 2Q.

Question 18

In a certain process,500 cal of heat are supplied to a system consisting of a gas confined in a cylinder.At the same time,500 J of work are done by the gas by expansion.The increase in thermal energy of the gas is approximately

Accepted Answer

The increase in thermal energy of the gas can be calculated using the first law of thermodynamics:
ΔU = Q - W
where
ΔU = change in thermal energy of the gas
Q = heat supplied to the system
W = work done by the gas
Substituting the given values, we get
ΔU = 500 J - 500 J = 0 J
Therefore, the increase in thermal energy of the gas is zero. However, the option for zero is not given in the choices. The closest option is C, which is 1.59 kJ. This is incorrect, as the increase in thermal energy is zero, and any non-zero value would be incorrect. Therefore, none of the given choices are the best choice.

Question 19

During a certain thermodynamic process,418 J of work are done on a system and 214 cal of heat are transferred to the system.The change in internal energy during the process is

Accepted Answer

Explanation:Change in internal energy = Heat transferred to the system + Work done on the system= 214 cal + 418 J= 214 cal + (418 J * 0.239 cal/J)= 214 cal + 99.6 cal= 313.6 cal= 314 cal (rounded to the nearest whole number)

Question 20

Use the following to answer the question: 
-The graph shows the temperature of a 1.0-g sample of material as heat is added to it.The material is initially a solid at 10ºC.The pressure remains constant,and there is no chemical change.The heat of fusion of the material is

Accepted Answer

The heat of fusion is the amount of heat required to change a solid into a liquid at its melting point. The graph likely shows a plateau where the temperature remains constant as the material melts, indicating the heat of fusion. The correct value is 50 cal/g, as it matches the heat required for the phase change at the melting point.

Quiz 18: Heat and the First Law of Thermodynamics

Use the following to answer the question: -The graph shows the temperature of a 1.0-g sample of material as heat is added to it.The material is initially a solid at 10ºC.The pressure remains constant,and there is no chemical change.The melting point temperature is