Question

Do you expect delta s to be positive negative or zero for the reaction
H2+I2 GIVES 2HI

Answer 1

ΔS for the given reaction is expected to be positive.

Explanation:

"The second law of thermodynamics states that the total entropy of a system either increases or remains constant; it never decreases." Entropy is zero for a reversible process while it increases for an irreversible process. Entropy is also defined as measure of randomness.

Now, coming back to the question, entropy for given reaction cannot be negative. Since the reaction is reversible, and ideal reactions do not exist, ΔS for the given reaction is greater than zero.

Entropy is calculated by standard entropy values at given temperatures. formula for entropy calculation is - ΔS = ∑S(product) - ∑S(reactant).