Molecular Physics | Thermodynamics Answers

A steady flow of steam enters a condenser with a specific enthalpy of 2300 kJ/kg and a velocity of 350 m/s. The condensate leaves the condenser with a specific enthalpy of 160 kJ/kg and a velocity of 70 m/s. Calculate the heat transfer to the cooling fluid per kilogram of steam condensed.

An inventor claims to have constructed an engine that has an efficiency of when operated 75% when operated between the boiling and freezing points of water. Is this possible ? Illustratively explain.

How much energy is released when 130.00 g of steam at 103.0 °C if cooled to ice at
–12.5 °C? Please show work

An Erlenmeyer flask of surface area 0.8 m2 and wall thickness 2 cm is filled with water at 0 oC. The Erlenmeyer flask is then immersed in a glass beaker filled with water at a temperature of 30 oC. What is the heat current? How long does it take for 12 J of heat energy to be transferred to the water in the Erlenmeyer flask?

3. A tank of volume 0.3 m3
contains 2 moles of helium gas at 20℃. Assuming the
helium behaves like an ideal gas,
3.1. Find the total internal energy of the system.
3.2. What is the average kinetic energy per molecule?

When a person plucks a guitar string the number of the half wavelengths that fit into the length of the string determines the ______ of the sound produced.

If a kettle is not 100% efficient where does the missing energy go? And is there a way of improving the efficiency of a kettle?

5.Some mass of a diatomic gas undergoes a compression process twice: first time - isothermally and second time – adiabatically. The gas is returned to the initial state before the second process. Each time the final pressure of the gas is n time greater than the initial pressure. Compare the work done by the gas in these two processes for two cases: n = 2 and n=100.

6.One mole of a monoatomic gas performs a cycle consisting of three processes: adiabatic expansion, isothermal compression, and isochoric heating. What work was done during adiabatic portion of this cycle, if the gas has consumed Q=10 kJ of heat during the isochoric portion? Draw the diagram of the process.

7.Assuming one knows the specific molar heat capacity of a gas at constant volume, calculate the specific molar heat capacity of the same gas in the process where the pressure is reversely proportional to the temperature: P=a/T.

3. n moles of an ideal gas undergo an isobaric process 1->2 and then the isochoric process 2->3 shown in Fig. 1 in such was that the gas performs work A. The ratio of P2 and P3 is known: P2/P3=k. The temperature T1 in the state 1 equals to the temperature T3 In state 3. Calculate temperature T3.

4. A monoatomic gas takes up a volume of V=4m3 and is at a pressure of 8x105 Pa. The gas undergoes an isothermal expansion reaching the final pressure of 1 atm. Calculate a) the work done to the gas in such a process b) the amount of heat absorbed by the gas c) change in the internal energy of the gas.

1. A gas undergoes a process 1->2 with the change in volume from V1=11 L to V2=1 L. The pressure in such a process changes linearly with volume: P=aV, where a=4000 Pa/m3 . Calculate the work done by the gas.

2. Consider a gas following a polytropic process PVn=const. Find the range of n such that the gas will cool down upon compression, and the range of n such that the gas will heat up upon compression. Draw the appropriate diagram.