Answer:
80.41 g
Explanation:
Data Given:
Mass of Nitrogen (N₂) = 77.3 g
Mass of Hydrogen (H₂) = 14.2 g
many grams of NH₃ = ?
Solution:
First we look at the balanced synthesis reaction
N₂ + 3 H₂ ------—> 2 NH₃
1 mol 3 mol
As 1 mole of Nitrogen react with 3 mole of hydrogen
Convert moles to mass
molar mass of N₂ = 2(14) = 28 g/mol
molar mass of H₂ = 2(1) + 2 g/mol
Now
N₂ + 3 H₂ ------—> 2 NH₃
1 mol (28 g/mol) 3 mol(2g/mol)
28 g 6 g
28 grams of N₂ react with 6 g of H₂
So
if 28 grams of N₂ produces 6 g of H₂ so how many grams of N₂ will react with 14.2 g of H₂.
Apply Unity Formula
28 g of N₂ ≅ 6 g of H₂
X g of N₂ ≅ 14.2 g of H₂
Do cross multiply
X g of N₂ = 28 g x 14.2 g / 6 g
X g of N₂ = 66.3 g
As we have given with 77. 3 g of N₂ but from this calculation we come to know that 66.3 g will react with 14.2 g of hydrogen and the remaining 10 g N₂ will be in excess
So, Hydrogen is limiting reactant in this reaction and the amount of NH₃ depends on the amount of hydrogen.
Now
To find mass of NH₃ we will do following calculation
Look at the reaction
As we Know
N₂ + 3 H₂ ------—> 2 NH₃
6 g 2 mol
So, 6 g of hydrogen gives 2 moles of NH₃, then how many moles of NH₃ will be produce by 14.2 g
Apply Unity Formula
6 g of H₂ ≅ 2 mol of NH₃
14.2 g of H₂ ≅ X mol of NH₃
Do cross multiply
X mol of NH₃= 14.2 g x 2 mol / 6 g
X mol of NH₃ = 4.73 mol
So, 14.2 g of hydrogen gives 4.73 moles of NH₃
Now
Convert moles of NH₃ to mass
Formula will be used
mass in grams = no. of moles x molar mass . . . . . . (2)
Molar mass of NH₃
Molar mass of NH₃ = 14 + 3(1)
Molar mass of NH₃ = 14 + 3 = 17 g/mol
Put values in equation 2
mass in grams = 4.73 mole x 17 g/mol
mass in grams = 80.41 g
mass of NH₃= 80.41 g
= 71.2 g