Question

A fertilizer is 60.9% ammonium phosphate. What is the percent P in the sample? Answer in units of %

Answer 1

Answer:- 12.7%

Solution:- It says, ammonium phosphate is 60.9%. It means if we assume 100 g of the sample then there is 60.9 g ammonium phosphate in it.

Formula of ammonium phosphate is $(NH_4)_3PO4$ and it's molecular weight is 149 grams per mol. There is only one P in the formula and so the mass of P in 149 g of ammonium phosphate is 31 g(atomic mass of P).

Now, we could use the proportions to find out the mass percentage of P in the sample.

31 g P is present in 149 g of ammonium phosphate, how many grams of P would be present in 60.9 g of ammonium phosphate. Let's set the proportions as:

$\frac{31}{149}=\frac{x}{60.9}$

$x=\frac{31(60.9)}{149}$

$x=12.7$

This 12.7 g of phosphorous is present in 100 g of the sample means there is 12.7% phosphorous in the sample.