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.

 

[LudusRex]

Dear Rajini,

Calculating the stoichiometric ratio for a compound involves determining the relative amounts of each element needed to form the desired compound. In this case, the compound in question is Nd[O0.89F0.11]FeAs. To calculate the stoichiometric ratio, you will need to know the molar mass of each element and the desired molar ratio of the compound.

The molar mass of Nd is 144.24 g/mol, O is 16.00 g/mol, F is 19.00 g/mol, Fe is 55.85 g/mol, and As is 74.92 g/mol. The desired molar ratio of the compound is 1:0.89:0.11:1:1, meaning for every 1 mole of Nd, there should be 0.89 moles of O, 0.11 moles of F, 1 mole of Fe, and 1 mole of As.

To calculate the amount of each compound needed, you can use the following formula:
Mass of compound = (Molar ratio of compound x Desired molar ratio x Total mass of all compounds) / Molar mass of compound

For Nd, the mass would be:
Mass of Nd = (1 x 1 x Total mass of all compounds) / 144.24 g/mol

Similarly, you can calculate the masses of O, F, Fe, and As using their respective molar ratios and molar masses. Once you have calculated the masses of each compound, you can then convert them to the appropriate amount of powder needed based on the purity of the starting chemicals.

As for the balanced equation, it is not provided in the paper you mentioned. However, you can use the stoichiometric ratio and the molar ratios to write a balanced equation for the synthesis reaction. It would look something like this:

Nd + (0.89/1)O + (0.11/1)F + Fe + As → Nd[O0.89F0.11]FeAs

I hope this helps with your synthesis process. Good luck!

Best regards,