Question

A cylinder contains a mixture of gases under constant atmospheric pressure. The gases undergo a chemical reaction. Upon reacting, the gases absorb 877 J of heat from the surroundings and the surroundings do 0.248 kJ of PV work on the gases. What is the value of delta H in joules for this process?​

Answer 1

The total change in enthalpy (ΔH) can be calculated using the equation: ΔH = q + w, where q is the heat absorbed by the system and w is the work done on or by the system. In this case, the gases absorb 877 J of heat and the surroundings do -248 J of work on the gases. Therefore, the value of ΔH is 629 J.

Step-by-step explanation:

The total change in enthalpy (ΔH) can be calculated using the equation: ΔH = q + w, where q is the heat absorbed by the system and w is the work done on or by the system. In this case, the gases absorb 877 J of heat from the surroundings and the surroundings do 0.248 kJ (or 248 J) of work on the gases.

Since work is done BY the surroundings ON the gases, the work term should be negative. Therefore, the work done by the system on the surroundings is -0.248 kJ (or -248 J).

Thus, the total change in enthalpy (ΔH) is equal to the sum of the heat absorbed and the work done by the system:

ΔH = q + w = 877 J + (-248 J) = 629 J.