Exam 18: Heat and the First Law of Thermodynamics

Use the following to answer the question: -One mole of an ideal gas ( $\gamma$ = 5/3)expands adiabatically and quasistatically from a pressure P₁ = 3 atm and a temperature of 30ºC to a pressure P₂ = 1 atm.How much work is done by the gas during this process? R = 8.314 J/mol·K = 8.206 L·atm/mol·K.

A group of explorers in the Antarctic can obtain the water they need only by melting snow.How much heat does it take for them to make a cup of coffee (100 g water at 100ºC)? Assume that the snow has an initial temperature of -40ºC; that the latent heats of fusion and vaporization of water are,respectively,333.5 kJ/kg and 2257 kJ/kg; and that the specific heats of ice (snow)and water are,respectively,2.05 kJ/kg · K and 4.18 kJ/kg · K.

From the measured molar heat capacities and the equipartition theorem,for a diatomic gas molecule the number of degrees of freedom from rotational motion are

Aluminum has a specific heat more than twice that of copper.Identical masses of aluminum and copper,both at 0ºC,are dropped together into a can of hot water.When the system has come to equilibrium,

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

When a substance changes phase,from solid to liquid or liquid to vapor and vice versa,there is no change in temperature,even though heat is being added or removed.Why is there no change in temperature?

Use the following to answer the question: -An ideal gas initially at 100ºC and pressure P₁ = 250 kPa occupies a volume V₁ = 4.5 L.It undergoes a quasistatic,isothermal expansion until its pressure is reduced to 150 kPa.How much does the internal energy of the gas change during this process? R = 8.314 J/mol·K = 8.206 L·atm/mol·K.

An ideal monatomic gas has a molar heat capacity C_mp at constant pressure.What is the molar heat capacity at constant volume of an ideal diatomic gas?

The internal energy of a solid depends on the number of degrees of freedom available to each atom.Which of the following statements is correct concerning these degrees of freedom in a solid?

The difference in the molar heat capacity at constant P and constant V is (assume ideal gas).

The specific heat of a gas at constant pressure is

If 100 g of steam at 100 ^$\circ$ C were mixed with 10 kg of ice at -100 ^$\circ$ C,find the final temperature of the mixture assuming no heat losses to the surroundings.

A system has a heat capacity of 100 J.This means

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

"The specific heat of an ideal gas at constant pressure C_p is greater than the specific heat of a gas at constant volume C_v." Which of the following describes this statement?

Glass beads of mass 100 g and specific heat 0.20 cal/g · Cº are heated to 90ºC and placed in a 300-g glass beaker containing 200 g of water at 20ºC.When equilibrium is reached,the temperature is approximately

At a particular point on a PV diagram,the magnitude of the slope of a curve that represents an adiabatic process is

Use the following to answer the question: -An ideal gas initially at 50ºC and pressure P₁ = 100 kPa occupies a volume V₁ = 3 L.It undergoes a quasistatic,isothermal expansion until its pressure is reduced to 50 kPa.How much does the internal energy of the gas change during this process? R = 8.314 J/mol·K = 8.206 L·atm/mol·K.

A cylinder contains 20 L of air at 1 atm.The ratio of C_p to C_V for air is 1.41.If this sample of air is compressed adiabatically to a volume of 5 L,the pressure after compression is approximately

A 3-kg mass of metal of specific heat = 0.1 kcal/kg ^$\circ$ C at a temperature of 600 ^$\circ$ C is dropped into 1.0 kg water at 20 ^$\circ$ C.With no heat losses to the surroundings,determine the equilibrium temperature of the mixture,and if it is 100 ^$\circ$ C,calculate what mass of water is turned into steam at this temperature.