Temperature change, colour change, releasing gas, bubbles and change in odor
Natural: Land mounds, Rivers
Human made: Country borders, cities
Answer:
The correct answer is B. It is spontaneous only at low temperatures.
Explanation:
In thermodynamics, the Gibbs free energy is a thermodynamic potential that can be used to calculate the maximum of reversible work that may be performed by a thermodynamic system at a constant temperature and pressure.
The spontaneity of a reaction is given by the equation:
ΔG = ΔH - TΔS
where:
ΔH: enthalpy variation
T: absolute temperature
ΔS: entropy variation
As the reaction is exothermic, ΔH<0
As the reaction order increases (the reagents are solid and gas and their product is solid), ΔS<0
Therefore, the reaction will be spontaneous when ΔG is negative.
ΔG = ΔH - TΔS
That is, the entropy term must be smaller than the enthalpy term.
Hence, the reaction will be spontaneous only at low temperatures.
n(2Fe2O3)=10g/319.374amu=0.03mol
n(4Fe+3O2)=0.03 mol
m(4Fe+2O2)=Mn=319.374×0.03=9.58=10
comets, astroids oort clouds which surround the kuiper belt
