Your mug contains 300 ml of coffee at 90 ° C. The coffee is too hot to drink. You decide to cool the coffee by dropping ice cubes at -20 ° C in the coffee. How many grams of ice do you need to add to the coffee to cool it down to 60 ° C?

A)2.00 g of helium gas at 100 ° C and a pressure of 1.00 atm expand in an isobar process so that the volume of the gas doubles. Helium is a monatomic gas with a molar mass of 4.00 g per mole.
Find the following:
1.the temperature of the gas after expansion
2. work performed on the gas
3.the heat added to the gas
4.the change in the internal energy of the gas

B) Your mug contains 300 ml of coffee at 90 ° C. The coffee is too hot to drink. You decide to cool the coffee by dropping ice cubes at -20 ° C in the coffee. How many grams of ice do you need to add to the coffee to cool it down to 60 ° C?
C) Make a simplified sketch of a thermal power machine where sizes W, Qh and Qc are included. Define the sizes and write down the expression for the efficiency of the thermal power machine.

D) A Carnot thermal power machine works between 500 ° C and 100 ° C. The Carnot machine is supplied with 250 J in each cycle. Find the efficiency of the Carnot machine. How many cycles does the machine have to go through to lift a stone with a mass of 500 kg to a height of 100 m?

E) Find the entropy change for each of the reservoirs in the Carnot machine (D) for single cycle. What is the entropy change of the universe for this cycle? Comment on the answer.

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