Experiment: Gravimetric Determination of Phosphorus in Fertilizer Samples

Question

1. Can NH4Cl be used as a substitute to precipitate the phosphorus in the sample? Why or why not?
- I think, NH4Cl can be used although I'm not quite sure if Cl- ions have some effects to the precipitation process. Am I right? Can NH4Cl be used for homogeneous precipitation?

I am not familiar with a homogeneous pptn method for the determination of P in fertilizer. The gravimetric method most often used in my experience is the pptn of MgNH4PO4*6H2O but that isn't done homogeneously unless your procedure does that. The NH4Cl in your question might be used to help buffer the solution for solutions that are too acid or too basic do not ppt the desired substance. You may want to clarify your question by posting a summary of the procedure but from what I know about P determinations, I don't think NH4Cl can be used as a substitute to ppt P.

Answer 1

I think it isn't possible because....

NVM.

Answer 2

How much heat is evolved if 2 moles of C3H8 is burned?