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a) An ideal gaseous reaction (which is a hypothetical gaseous reaction that conf

ID: 971307 • Letter: A

Question

a) An ideal gaseous reaction (which is a hypothetical gaseous reaction that conforms to the laws governing gas behavior) occurs at a constant pressure of 40.0 atm and releases 55.1 kJ of heat. Before the reaction, the volume of the system was 7.40 L . After the reaction, the volume of the system was 3.00 L .

Calculate the total internal energy change, E, in kilojoules.

b)

An ideal gas (which is is a hypothetical gas that conforms to the laws governing gas behavior) confined to a container with a massless piston at the top. (Figure 2)  A massless wire is attached to the piston. When an external pressure of 2.00 atm is applied to the wire, the gas compresses from 6.40 to 3.20 L . When the external pressure is increased to 2.50 atm, the gas further compresses from 3.20 to 2.56 L .

In a separate experiment with the same initial conditions, a pressure of 2.50 atm was applied to the ideal gas, decreasing its volume from 6.40 to 2.56 L in one step.

If the final temperature was the same for both processes, what is the difference between q for the two-step process and q for the one-step process in joules?

Explanation / Answer

From 1st law of Thermodynamics,
deltaU = q - PdeltaV = 55.1 kJ - 40atm*(3.00-7.40)L = 55.1 + 176 L-atm = 55.1 + 17.6 kJ = 72.7 kJ