Molecular Physics | Thermodynamics Answers

When you are purchasing clothes ,seller measure it's area using meter scale made of steel . When you buy in winter it was ok but when you buy in summer you will get what:
Loss
Profit
Nothing

Carnot refrigeration cycle absorbs heat at 280k and rejects heat at 310k.
a: Calculate the coefficient of performance of this refrigeration cycle.
b: If the cycle is absorbing 1120KJ/min at 280k, how many KJ work is required per second .
C: If the carnot heat pump operates between the same temperature as the above refrigerator, what is the coefficient of performance ?
d: How many KJ/min will the heat pump deliver at 310k if it absorb 1120 KJ/min at 280k.

A Carnot engine has a power output of 163 kW. The engine operates between two reservoirs at 31◦C and 469◦C.
1. How much thermal energy is absorbed each hour? Answer in units of J.
2. How much thermal energy is lost per hour? Answer in units of J.

A steam engine (assume a Carnot engine ) has an efficiency of 34.8%.
If the waste heat has a temperature of 76◦C, what is the temperature of the boiler?
Answer in units of ◦C.

An engine absorbs 2364 J from a hot reservoir and expels 881 J to a cold reservoir in each cycle.
1. What is the engine’s efficiency?
2. How much work is done in each cycle? Answer in units of J.
3. What is the mechanical power output of the engine if each cycle lasts for 0.32s? Answer in units of kW.

An engine using 1 mol of an ideal gas initially at 19 L and 331 K performs a cycle consisting of four steps:
1) an isothermal expansion at 331 K from 19 L to 39.4 L ;
2) cooling at constant volume to 218 K ;
3) an isothermal compression to its original volume of 19 L; and
4) heating at constant volume to its original temperature of 331 K .
Find its efficiency. Assume that the heat capacity is 21 J/K and the universal gas constant is 0.08206 L · atm/mol/K = 8.314 J/mol/K.
Answer in units of %.

2.9 cm3 of water is boiled at atmospheric pressure to become 5271.2 cm3 of steam, also at atmospheric pressure.
1. Calculate the work done by the gas during this process. The latent heat of vaporization of water is 2.26 × 106 J/kg. Answer in units of J.
2. Find the amount of heat added to the water to accomplish this process. Answer in units of J.
3. Find the change in internal energy. Answer in units of J.

An ideal gas initially is allowed to expand isothermally until its volume is 0.75 L and its pressure is 8 kPa. Then it is heated at constant volume until its pressure is 1 kPa.
1. Calculate the work done by the gas. Answer in units of kJ.
2. Find the heat added to the gas during this process. Answer in units of kJ.

Two moles of helium gas initially at 273 K and 0.31 atm are compressed isothermally to 1.55 atm.

1. Find the final volume of the gas. Assume that helium behaves as an ideal gas. The universal gas constant is 8.31451 J/K · mol.
Answer in units of m3.

2. Find the work done by the gas. Answer in units of kJ.

3. Find the thermal energy transferred. Answer in units of kJ.

calculate the change in melting point of ice when it is subjected to a pressure of 100 atm. Density of ice is 0.917g/c.c and latent heat of ice is 336J/g
Answer :72.26k