Exam 18: Heat and the First Law of Thermodynamics

A liquid is irregularly stirred in a well-insulated container and thereby undergoes a rise in temperature.Regarding the liquid as a system,you can say that

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

To raise the temperature of a 2.0-kg piece of metal from 20º to 100ºC,61.8 kJ of heat is added.What is the specific heat of this metal?

Calculate the speed of sound in hydrogen gas (H₂)at 20 ^$\circ$ C given the ratio of C_p to C_v is 1.41.(Molar mass of H₂ = 2 g/mol.)

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

The work done by an ideal gas in an isothermal expansion from volume V₁ to volume V₂ is given by the formula: Standard atmospheric pressure (1 atm)is 101.3 kPa.If 1.0 L of He gas at room temperature (20ºC)and 1.0 atm of pressure is compressed isothermally to a volume of 100 mL,how much work is done on the gas?

Use the following to answer question: -Heat is added to a substance at a constant rate.The substance starts as a solid and is melted; the liquid is heated and vaporized; finally,the vapor is heated.This process is shown in the graph.The latent heat of fusion can be found by

A 1.0-kg piece of marble at 100ºC is dropped into 2.5 kg of water at 1.0ºC and the resulting temperature is 7.0ºC.The specific heat of the marble is approximately

A container contains a 200 mL of 100% proof alcohol (i.e.,it has 50% ethyl alcohol and 50% water by volume)at 20 ^$\circ$ C.How much heat is needed to bring the mixture to the boiling point of the alcohol? (assume that the specific heat in the 100% proof can be treated as due to the alcohol and water separately,and the density,boiling point and specific heat of alcohol are 0.81 g/cm³,78 ^$\circ$ C,and 2.4 J/(g.C ^$\circ$ ),respectively)

Use the following to answer question: -Heat is added to a substance at a constant rate.The substance starts as a solid and is melted; the liquid is heated and vaporized; finally,the vapor is heated.This process is shown in the graph.Which of the following statements is correct?

The molar heat capacity at constant volume of a gas is found to be 20.74 J/mol · K.What is the molar heat capacity at constant pressure of this gas? (The ideal-gas law constant is R = 8.31 J/mol · K)

A gas can absorb heat without changing temperature if at the same time

On a hot summer day,water collects on the outside of a glass of ice lemonade.The water comes from

Which of the following statements about heat and work is the proper usage of the terms?

A system is said to go through an adiabatic process if,throughout the process,

A 250-g piece of lead is heated to 100ºC and is then placed in a 400-g copper container holding 500 g of water.The specific heat of copper is c = 0.386 kJ/kg · K.The container and the water had an initial temperature of 18.0ºC.When thermal equilibrium is reached,the final temperature of the system is 19.15ºC.If no heat has been lost from the system,what is the specific heat of the lead? (the specific heat of water is 4.180 kJ/kg · K)

The pressure of a gas in an isobaric expansion remains constant.In such an expansion,

At liquid ⁴He temperatures (< 4.2 K),the molar heat capacity heat of most insulators goes as C = AT³,where A is a constant and T is in kelvins.The ratio of the heat required to raise the temperature from 2 K to 3K and from 1 K to 2K is

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?

A 2.0-kg mass of iron (specific heat = 0.12 kcal/kg · Cº)at a temperature of 430ºC is dropped into 48 kg of water.The water is initially at a temperature of 10ºC.With no heat losses to the surroundings,the equilibrium temperature of the iron and water is approximately