Answer to Question #313788 in General Chemistry for kelly

Question

2. The work done to compress a gas is 74 J. As a result, 26 J of heat is given off to the surroundings. Calculate the change in energy of the gas.

Answer 1

Work done to compress a gas = 74 J.

q = 26 J

Here, the gas is compressed where the heat is released by the gas to the surroundings. This an exothermic process. Hence, the work done gets + sign and heat (q) gets - sign.

The change in energy of the gas is calculated using the formula:

                 ΔU = q + w

        q = heat

        w = work done

Therefore, change in energy of gas will be:

 ΔU = q + w

    = −26 J + 74 J

    = 48 J

Hence, the change in energy of the gas is 48 J.