Question

Ammonium dihydrogen phosphate, formed from the reaction of phosphoric acid with ammonia, is used as a crop fertilizer as well as a component of some fire extinguishers, (a) What are the mass percentages of N and P in the compound? (b) How much ammonia is incorporated into 100. g of compound?

Answer 1

Answer:

a)The mass percentages of nitrogen and phosphorus in the compound is 24.34% and 26.95% respectively.

b) 14.78 grams ammonia is incorporated into 100. g of compound.

Explanation:

a) Ammonium dihydrogen phosphate that is $NH_6PO_4$.

Molecular mass of ammonium dihydrogen phosphate = M

M = 115 g/mol

Percentage of an element in a compound:

$\frac{\text{Number of atoms of element}\times \text{Atomic mass of element}}{\text{molecular mass of element}}\times 100$

Percentage of nitrogen:

$\frac{1\times 28 g/mol}{115 g/mol}\times 100=24.34\%$

Percentage of phosphorus:

$\frac{1\times 31g/mol}{115 g/mol}\times 100=26.95\%$

b) Percentage of ammonia in 1 molecule of ammonium dihydrogen phosphate.

Molar mass of ammonia = 17 g/mol

$\%=\frac{17 g/mol}{115 g/mol}\times 100=14.78\%$

Amount of ammonia in 100 grams of compound:

14.78% of 100 g of ammonium dihydrogen phosphate:

$\frac{14.78}{100}\times 100 g=14.78 g$

14.78 grams ammonia is incorporated into 100. g of compound.