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Posted

Hello,
I need to calculate the yield % of [(Ph)3PH]2[CoCl4]

The actual yield is 2.715g
My issue is with the theoretical yield, here is how I did it:

I'm following this reaction that was given in the explanations of my homework; (C6H5)3P + HCl => (C6H5)3PH+ + Cl-

Molar mass of (C6H5)3P: 262.29 g/mol
Molar mass of (C6H5)3PH+: 263.30 g/mol
Mass of Triphenylphosphine measured: 1.062 g

n(triphenylphosphine)=m(triphenylphosphine)/M(triphenylphosphine) =1.062g/(262.29 g/mol)=4.049×10-3 mol

Molar mass of [(Ph)3PH]2[CoCl4] : 727.33 g/mol
Since there are 2 molecules of (Ph)3PH in the [(Ph)3PH]2[CoCl4], the n(triphenylphosphine) needs to be divided by  2.

n([(Ph)3PH]2[CoCl4])=n(triphenylphosphine)/2=2.025×10-3 mol

m[(Ph)3PH]2[CoCl4] =n[(Ph)3PH]2[CoCl4] ×M[(Ph)3PH]2[CoCl4]

m[(Ph)3PH]2[CoCl4] =(2.025x10-3 mol)×(727.33 g⁄mol)
m[(Ph)3PH]2[CoCl4] =1.479 g = Theoretical yield

You see, my theoretical yield is smaller than my actual yield.
If someone sees my mistake, please let me know.

Thank you,
MV101

Posted

So far, I have not found an error.  I did see one thing that bothered me a bit, and it could be a clue.  It is difficult to see how the protonated form of a phosphine could be a ligand to the metal ion.  The unprotonated form would be fine.

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