Question

(a) In a chemical reaction 3 moles of one gas and 2 moles of a second gas react to form 4 moles of a third gas and 2 moles of liquid. Would you expect DS to be positive, negative, or close to zero for this reaction? DS for this reaction should . (b) In which of the processes described below should the entropy increase? Choose all of the correct possibilities. ice cubes melting at -5 oC and 1 atm pressure separating a mixture of nitrogen and oxygen gases into pure nitrogen and pure oxygen detonation of some dynamite some dry ice left on a tabletop disappearing via sublimation the reaction of nitrogen atoms to form N2 molecules at 25 oC and 1 atm

Answer 1

a)Entropy change will be -ve since from gas (most unorganized) to liquid product ( most organized ) is formed,. More over the number of moles of products are higher than reactants. Hence entropy change is negavtive.

b) entropy change is +ve for melting ice since heat is addded. b) air separating into nitrogen and oxygen   entropy change is +ve and sublimation of ice, heat is to be added and hence entropy change is - ve. During explosion entropy increases. Entropy change is -ve during formation of N2 gas from Nitrogen atoms.