There's missing information on the mass of the ammonia. As an example, let's use it at 4.5 g. The calculus will be the same, just substitute the mass for the one given in the question.
Answer:
13.15 g
Explanation:
The reaction is given by the equation:
H₃PO₄ + 3NH₃ → (NH₄)₃PO₄
The molar mass of ammonia is 17 g/mol, and the molar mass of ammonium phosphate is 149 g/mol. The stoichiometry of the reaction is:
3 moles of NH₃ ----------------- 1 mol of (NH₄)₃PO₄
3*17 = 51 g of NH₃ -------------------- 1*149 = 149 g of (NH₄)₃PO₄
4.5 of NH₃ -------------------- x
Here, 4.5 g must be substituted by the mass given in the question.
Then, by a simple direct three rule:
51x = 149*4.5
51x = 670.5
x = 13.15 g
