1. You have a 16 oz cup of coffee at 180 degrees F. That is way too hot to drink. So you want to cool the coffee off and decide to add some cold water. You add 2 ounces of cold water at 40 degrees F. How much will the water you added heat up? How much will the coffee that you poured the water into cool down?

2. An air bubble at the bottom of a lake has a volume of 15 cm3. The lake is 40 m deep and has a temperature of 4 ºC at the bottom. The bubble then rises to the surface where the temperature is 23 ºC. What is the volume of the bubble just before it reaches the surface?

3. You are sitting behind a curtain watching meters that measure pressure, volume, and temperature of some kind of heat engine. Pressure, volume, and temperature have reached an equilibrium state. Then someone behind the curtain tells you that they are going to add energy to the system. The energy is added and the equilibrium changes. Can you tell whether they did work on the system, heated the system, or a combination of both? Explain your answer.

4. In a refrigerator, heat is transferred from a colder area (the inside of the refrigerator) to a warmer area (the air outside of the refrigerator). Given what you know about internal energy, explain how this is possible.

Solution Summary

Solutions to math problems involving heat and thermodynamics are outlined in fine detail.

An ideal gas mixture consists of 3 kg of Ar and 6 kg of CO2 gases. The mixture is now heated at constant volume from 250 K to 350 K. The amount of heat transfer is:

(Please see the attachment for detailed problem description)
Distinguish between reversible and irreversible processes in thermodynamics. Describe the circumstances under which a) dQ = Tds and dW = -PdV.
A long cylinderical rod of radius R is attached to a source of heat at one end and its surroundings are at temperature

Provide an explanation of the meaning of the first and second laws of thermodynamics. Then using the second law, explain why a barrel of oil can be used only once as a fuel source, why can we not recycle high-quality energy resources.

Calculate δH and δStotal when two iron blocks each with mass of 1.00kg, one at 25'C and one
at 250'C are placed in contact with each other in an isolated container. The specific heat capacity of iron is 0.449 J/'C*gram and can be assumed to be constant over this temperature range.

Thermodynamics: Due to design changes, the efficiency of an engine decreases from 0.23 to 0.42. For the same input heat Qh. These changes increase the work done by the more efficient engine and reduce the amount of heat rejected to the cold reservoir. Find the ratio of heat rejected to the cold reservoir.

A 2-kW baseboard electric resistance heater in a vacant room is turned on and kept on for 15 min. The mass of the air in the room is 75 kg, and the room is tightly sealed so that no air can leak in or out. The temperature rise of air at the end of 15 min is:

An ice cube weighs 30 grams at 0 degrees Celsius. It is added to 200 g of water at 80 degrees Celsius in an insulated container. What is the final temperature of the mixture? The affect of the container is negligible.

Please help with the problems involving applied heatthermodynamics.
3. Calculate the change in enthalpy during a compression process in which the work done on the working medium is 24 kJ, and the change in internal energy is 36 kJ.
Heat added or rejected
4. Derive the numerical ratio ----------------------------

Two reversible heat engines X and Y are arranged in series. The engine X rejected heat directly to Y. Engine X receives 400 KJ of heat at 427 degrees centigrade from a high temperature source. Engine Y rejects heat to a sink at 7 degree centigrade. If the output of X is twice that of Y, find the efficiency of each engine, the he

In moving out of a dormitory at the end of the semester, a student does 1.6 x 10^4 J of work. In the process, his internal energy decreases by 4.2 x 10^4 J. Determine each of the following quantities (including the algebraic sign): (a)W, (b) delta U, and (c)Q.