Calculate the entropy change for the reaction: fe2o3(s) + 2al(s) -> al2o3(s) + 2fe(s)
entropy data:
fe2o3(s): 90 j/k mol
al(s): 28.3 j/k mol
al2o3(s): 51 j/k mol
fe(s): 27.2 j/k mol

ΔSº= -41,2 J/molK

Explanation:

For a general equation aA +bB → cC + dD

ΔSº= c*SºC + d*SºD - a*SºA - b*SºB

ΔSº=  SºAL2O3 + 2SºFe - SºFe2O3 - 2SºAl = (51 + 54.4 - 90 - 56.6)J/molK = -41,2 J/molK

8 m/s because for him to get the same amount of energy as ray is putting out, bobby, who weighs half as much as ray, needs to run twice as fast.