What is the coefficient of O2 ? 5 O 10 11 O 4 FeS2 + 02 --> - Fe2O3 + SO2 - For a system that gains thermal energy and does work on the surroundings, heat (q) is negative and work (w) is positive. heat (q) is positive and work (w) is negative. heat (q) and work (w) are both negative. heat (q) and work (w) are both positive.