Consider the following cyclic process carried out in two steps on a gas. Step 1: 50. J of heat is added to the gas, and 13 J of expansion work is performed. Step 2: 56 J of heat is removed from the gas as the gas is compressed back to the initial state. Calculate the work for the gas compression in Step 2.

Work for the gas compression is 93 J.

Explanation:

The change in internal internal energy during the whole cycle will be 0 as internal energy is a state function.

According to first law of thermodynamics,

where, represents change in internal energy, q is the heat exchanged and w is work done.

Here,  ( q is positive for addition of heat and w is negative for work don by system)

  (q is negative for removal of heat)

or, w = 93 J

quartz

explanation:

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.