R1.4.1 Predict the entropy change for a given reaction or process [HL IB Chemistry]

Remember that ENTROPY can also be thought of as DISORDER. Gas has the highest entropy in IB chemistry, so any reaction that produces gas will have a positive value of delta S, whereas any reaction that uses up gas will have a negative delta S. This is an oversimplification, e.g. what happens if both product and reactants are gaseous -- watch the vid!