What are the signs of ΔH, ΔS, and ΔG for the spontaneous conversion of a crystalline solid into a gas?

ΔH>0, ΔS>0, and ΔG<0

Explanation:

Crystalline solid → Gas

using Gibbs equation

ΔG = ΔH - TΔS

as ΔG < 0 and ΔS > 0

ΔH - TΔS <0

ΔH < TΔS ⇒ΔH >0

This gives that ΔH will be Positive but it will be less than TΔS. So we need to provide some energy to convert crystalline solid into gas.

So one mole of Fe2O3 contains two moles of Fe3+ ions.

Explanation:

As there is an internal mole ratio of 2:3

It means that there are 2moles of iron within every mole of iron(III) oxide.

Iron III oxide is an ionic compound composed of Fe3+ ions and O2- ions. According to the formula, there are three O2- ions for every two Fe3+ ions.

Extra:

One 'unit' of Fe2O3 has two Fe3+ ions and three O2- ions, hence a dozen Fe2O3 contains two dozen Fe3+ ions and three dozen O2- ions, and a mole Fe2O3 contains two moles Fe3+ ions and three moles O2- ions.