Stoichiometric ratio calculation

[Rajini]

Dear all,

I am trying to synthesis a compound as given the paper below. Can someone help me of how to calculate the stoichiometric ratio and amount of each compound (i.e. Nd pieces, As, Fe, Fe₂O₃, FeF₃ powders) required to prepare the same compound as in that paper. Especially I don’t know the balanced equation.

Preparation of superconducting compound is given in the following paper:
Doi: 10.1209/0295-5075/82/57002
The superconducting compound is Nd[O_0.89F_0.11]FeAs.
It is mentioned in that paper as follows:
Nd pieces, As, Fe, Fe₂O₃,FeF₃ powders (the purities of all starting chemicals are better than 99.99%) were mixed together according to the nominal stoichiometric ratio of Nd[O_0.89F_0.11]FeAs, then ground thoroughly and pressed into small pellets.

thanks and regards, Rajini.

 

[Borek]

You can't balance a reaction in a standard way, when the compound has non-integer coefficients. But the stoichiometry still holds - 1 mole of Nd[O_0.89F_0.11]FeAs contains 1 mole of Nd, 1 mole of Fe, 1 mole of As, 0.89 moles of O and 0.11 moles of F. Assume you are going to make 1 mole. Start calculating how much Fe₂O₃ you need to get correct amount of oxygen, then how much FeF₃ for fluorides, then check how much Fe you already have and calculate how much Fe to add to make its total up to 1 mole. The rest should be obvious.

 

[Rajini]

solved

Hello Borek,

I got your suggestion:
Is the following correct?
Nd + As + 0.3699Fe + 0.2967 Fe₂O₃ + 0.0367 FeF₃ -> Nd[O_0.89F_0.11]FeAs.
I think I can now calculate grams of each compound reruired to prepare..
Regards, Rajini.

 

[Borek]

Looks OK to me.