# Calculating change in Gibbs Free Energy for a specific type of problem

Can anyone describe what is going on here? $$Si(liq.)=Si_{(1 weight percentFe)}$$ I have come across this statement quite a few times in Metallurgical Thermodynamics.All that they ask for is change in Gibbs free energy for the process.I am completely unable to figure why this particular model is so important for a sepecific question.It would be great if someone could interpret both the analytical and the mathematical analogy to this.

• It's not clear what "Metallurgical Thermodynamics" refers to. Please add a complete citation so that the context could be checked. Also, if $$Si(liq.)=Si(1 weight percent Fe)$$ is exactly how your source presents it, I'd say it's just poor formatting or the author doesn't know what they are writing about. Jan 15 '21 at 5:21
• @andselisk This is from Gaskell.I do not know why they are not conting the space during formatting. Jan 15 '21 at 6:11
• You may want to tinker with formatting. For instance, $$\ce{Si\textrm(liq)<=>Si{(1 \textrm{weight percent Fe})}}$$ is written as "\ce{Si\textrm(liq)<=>Si{(1 \textrm{weight percent Fe})}}" Jan 15 '21 at 9:17
• Is it not more convenient to write : $\ce{0.99 Si(liq) + 0.01 Fe -> Si_{0.99} Fe_{0.01}}$ ? Jan 15 '21 at 9:45
• @Maurice Correct but I feel the person wants to know why that is working Jan 15 '21 at 9:48