Question 2 Ammonium phosphate NH43PO4 is an important ingredient in many fertilizers. It can be made by reacting phosphoric acid H3PO4 with ammonia NH3. What mass of ammonium phosphate is produced by the reaction of 4.2g of ammonia? Round your answer to 2 significant digits.

The answer is 12.27 g (NH4)3PO4

Explanation:

Step 1: balance the chemical equation:

H3PO4 + 3NH3 → (NH4)3PO4

step 2: the molar masses of each of the reagents and products are calculated using the periodic table:

H3PO4:

3 atoms of H: 3x1=3 g/mol

1 atom of P: 1x30.97=30.97 g/mol

4 atoms of O: 4x16=64 g/mol

Molar mass=3+30.97+64=97.97 g/mol

3NH3:

3 atoms of N: 3x14=42 g/mol

9 atoms of H: 9x1=9 g/mol

Molar mass=42+9=51 g/mol

(NH4)3PO4:

3 atoms of N: 3x14=42 g/mol

12 atoms of H: 12x1=12 g/mol

1 atom of P: 1x30.97=30.97 g/mol

4 atoms of O: 4x16=64 g/mol

Molar mass=42+12+30.97+64=148.97 g/mol

we make a rule of three to calculate the amount of ammonium phosphate:

51 g NH3------------------148.97 g (NH4)3PO4

4.2 g NH3-----------------x g (NH4)3PO4

Clearing the x, we have: