Exam 12: The Laws of Thermodynamics

An electrical generating plant operates at a boiler temperature of 225°C and exhausts the unused heat into a nearby river at 25.0°C.If the generating plant has a power output of 850 megawatts (MW)and if the actual efficiency is 3/4 the theoretical efficiency,how much heat per second must be delivered to the boiler? (0°C = 273 K)

The surface of the Sun is at approximately 5 700 K and the temperature of the Earth's surface is about 290 K.What total entropy change occurs when 1 175 J of heat energy is transferred from the Sun to the Earth?

According to the second law of thermodynamics,which of the following applies to the heat received from a high temperature reservoir by a heat engine operating in a complete cycle?

The Carnot cycle consists of a combination of ____ and ____ processes.

A Carnot engine runs between a hot reservoir at T_h and a cold reservoir at T_c.If one of the temperatures is either increased or decreased by 3.5 K,which of the following changes would increase the efficiency by the greatest amount?

System 1 is 4.20 moles of a monatomic ideal gas held at a constant volume as it undergoes a temperature increase.System 2 is 4.20 moles of a diatomic ideal gas held at constant volume as it also undergoes a temperature increase.The thermal energy absorbed by System 1 is Q₁,and the thermal energy absorbed by System 2 is Q₂ as both systems undergo a temperature increase of 76.0 K.What is the ratio Q₁/Q₂?

​Two objects,A and B,are placed in thermal contact.The entropy of object A decreases.What can be said about the relationship between the temperatures of the two objects?

Six moles of an ideal gas, initially at 178 C, is compressed at a constant pressure of 2.00 atm to one-third its initial volume. -What is the work done on the gas during the compression?

Area on a PV diagram has units associated with

The adiabatic index of a gas is given by which of the following?

A heat engine receives 7 900 J of heat from its combustion process and loses 3 200 J through the exhaust and friction.What is its efficiency?​

A thermodynamic process that happens very quickly tends to be

Which of the processes on a monatomic ideal gas given below will result in the temperature of the gas increasing? W is the work done by the gas.

In an isobaric process 4.0 × 10⁴ J of work is done on a quantity of gas while its volume changes from 2.5 m³ to 1.5 m³.What is the pressure during this process?

A refrigerator has a coefficient of performance of 3.0.When removing 2.7 × 10⁴ J from inside the refrigerator,how much energy is sent into the environment?

The volume of an ideal gas changes from 0.40 to 0.51 m³ although its pressure remains constant at 52 000 Pa.What work is done on the system by its environment?

The specific heat at constant volume per mole of 3​R​/2 is for what type of molecule?

According to the first law of thermodynamics,the sum of the heat gained by a system and the work done on that same system is equivalent to which of the following?

Consider a Carnot cycle starting at the state of highest pressure and smallest volume.Call the isothermal expansion that starts at this state step 1,the adiabatic expansion which follows step 2,the isothermal compression that then follows step 3,and the adiabatic compression which returns the system to the initial state step 4.In which step does the entropy of the system increase?

A 5.0-mol ideal gas system undergoes an adiabatic free expansion (a rapid expansion into a vacuum),going from an initial volume of 20 L to a final volume of 30 L.How much work is done on the system during this adiabatic free expansion?