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What is the temperature range for which the formation of iron from rust is spontaneous?

The equation is: 2Fe2O3(s) → 4Fe(s) + 3O2(g)

Taking into account: ΔG = ΔH – TΔS

ΔH°f = 1648.4 kJ

ΔS°f = 549.6 J/K

2007-05-14 07:10:48 · 3 answers · asked by theweirdguy1 2 in Science & Mathematics Chemistry

3 answers

Above 2999.272 K

2007-05-14 07:27:42 · answer #1 · answered by ag_iitkgp 7 · 0 0

ΔG = ΔH - TΔS

a negative ΔG would depend on the sign of the changes in enthalpy (ΔH), entropy (ΔS), and the magnitude of the absolute temperature (in kelvins). Changes in the sign of ΔG cannot be changed directly by temperature, because it can never be less than zero.

When ΔS is positive and ΔH is negative, a process is spontaneous

When ΔS is positive and ΔH is positive, a process is spontaneous at high temperatures, where exothermicity plays a small role in the balance.

When ΔS is negative and ΔH is negative, a process is spontaneous at low temperatures, where exothermicity is important.

When ΔS is negative and ΔH is positive, a process is not spontaneous at any temperature, but the reverse process is spontaneous.

here ΔH ΔS are both +ve so your answer is HIGH TEMPRATURE RANGE.

2007-05-14 07:20:50 · answer #2 · answered by Anonymous · 0 0

no

2007-05-14 07:12:56 · answer #3 · answered by Anonymous · 0 1

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