Molecular Physics | Thermodynamics Answers

A closed system consisting of 1kg gaseous co² undergoes a reversible process at constant pressure causing a decrease of 30kj in internal energy

Determine the work done during the process

Take CP=840j/kg°c and CV=600j/kg°c

Water is heated in an open pan where the air pressure is 1.00 atmosphere. The water

remains a liquid, which expands by a small amount as it is heated. Calculate the ratio

of the work done by the water to the heat absorbed by the water.

A gas is contained in a chamber, as indicated in the figure below. Suppose the region

outside the chamber is evacuated and the total mass of the block and the movable

piston is 135 kg. When 2050 J of heat flows into the gas, the internal energy of the gas

increases by 1730 J. Calculate is the distance s through which the piston rises.

Three moles of an ideal monatomic gas are at a temperature of 345 K. Then, 2438 J of

heat is added to the gas, and 962 J of work is done on it. Calculate the final

temperature of the gas.

9. What is the pH 500 mL of solution containing 0.0124 grams of Ca(OH)2? 10. The pH of a solution is 4.80. What is the concentration of hydroxide ions in this solution? 11. A solution in which [H^+] = 10^-8 M has a pH of _ and is_. 12. The pH of a 0.02 M of an unknown weak acid is 3.7. What is the pKa of this acid? 13. What is the approximate pH of a solution labeled 0.050 M HClO? 14. What is the pH of a solution labeled 0.30 M (CH3)3N ? 16. A 0.10 M solution of a weak acid, Hx, is 0.059% ionized. Evaluate Ka for the acid. 17. What is the percent ionization of an 1.2 M HF solution?

in an air compressor the compression takes place at a constant interval energy and 50 kj of heat and rejected to the colling water for every kilogram of air. calculate the work input for the compression stoke per kilogram of air

Oxygen O2, at a pressure of 200 bars, will be contained in a steel container at a temperature of 20 oC.

The volume of the container is 0.04 m3. Assuming that O2 is an ideal gas, calculate the mass of O2 which can

be contained in the container.

The container is protected against excessive pressure by a fusible plug which will melt if the temperature

goes too high.

Calculate at what temperature the fuse plug will melt if the pressure is limited to 240 bar.

(The molar mass of oxygen = 32 Kg / Kmol and Ru = 8314 J / Kmol K)

1) Smoke from a burning rubbish heap is observed to move upwards in a wavy manner. Explain:

(i) why the smoke moves upwards

(ii) why the movement is wavy

(iii) how the movement of the smoke is different from Brownian motion


2) Hot tea from the same flask is served into two cups of the same shape and same volume, one made of glass and the other of silver. State, giving reasons in each case

(a) which cup of tea colds fast

(b) the method of heat transfer by which the two cups lose heat at the same rate

How much heat is absorbed by 60 g of copper when its temperature is

raised from 20 °C to 80 °C?(specific heat capacity of copper = 900 J/kgK)

a)Suba (m=72.6 kg) is skiing from a hill. She is standing at 28.5 m from the earth surface level.

i.Calculate Suba’s gravitational potential energy at the top.

ii.Calculate Suba’s kinetic energy at the top.

iii.Calculate total mechanical energy at the top.

iv.Calculate Suba’s kinetic energy and gravitational potential energy at the halfway down point from the top.

v.Calculate Suba’s kinetic energy at the bottom of the hill.

vi.Calculate Suba’s speed at the bottom of the hill.


b)The temperature of the water decreases to 0 °C in 10 minutes.

(specific heat capacity of water = 4200 J kg-1K–1)

Calculate,

i. the energy lost by the water when the temperature decreases to 0 °C.

ii. the average rate at which the water is losing energy, in J s–1.

iii. the time is taken for the water at 0 °C to turn completely into ice.

(The specific latent heat of fusion of water = 3.3 X 105 J Kg-1)