Ammonia contains 82.65% N and 17.65%hydrogen. If the law of constant proportions is true then calculate the mass of zinc required to give 10 gm of ammonia. Please I need a proper explain.

To tackle the problem of calculating the mass of zinc required to produce 10 grams of ammonia (NH₃), we first need to understand the composition of ammonia and the chemical reaction involved in its formation. Ammonia consists of nitrogen and hydrogen in a specific ratio, and we can use this information to find out how much zinc is necessary for the reaction.

Understanding Ammonia Composition

Ammonia is made up of nitrogen and hydrogen in the ratio of 82.65% nitrogen (N) and 17.65% hydrogen (H). To find the mass of each element in 10 grams of ammonia, we can calculate:

• Mass of nitrogen in 10 g of NH₃: 10 g × 0.8265 = 8.265 g
• Mass of hydrogen in 10 g of NH₃: 10 g × 0.1765 = 1.765 g

The Chemical Reaction

The formation of ammonia can be represented by the following chemical equation:

N₂ + 3H₂ → 2NH₃

This equation tells us that one mole of nitrogen reacts with three moles of hydrogen to produce two moles of ammonia. To find out how much zinc is needed, we need to consider the reaction where zinc reacts with an acid to produce hydrogen gas, which can then react with nitrogen to form ammonia.

Calculating Moles of Ammonia

Next, we need to determine how many moles of ammonia are present in 10 grams. The molar mass of ammonia (NH₃) is approximately 17 g/mol (14 g/mol for nitrogen and 3 g/mol for hydrogen). Therefore, the number of moles of ammonia in 10 grams is:

Moles of NH₃ = Mass / Molar Mass = 10 g / 17 g/mol ≈ 0.588 moles

Relating Moles of Ammonia to Moles of Zinc

To produce ammonia, we need to know how much zinc is required. The reaction of zinc with hydrochloric acid (for example) can be represented as:

Zn + 2HCl → ZnCl₂ + H₂

From this reaction, we see that one mole of zinc produces one mole of hydrogen gas. Since we need hydrogen gas to react with nitrogen to form ammonia, we can relate the moles of ammonia to the moles of hydrogen needed:

From the ammonia formation reaction, we know that:

• 2 moles of NH₃ require 3 moles of H₂

Thus, for 0.588 moles of NH₃, the moles of H₂ required would be:

Moles of H₂ = (3/2) × 0.588 ≈ 0.882 moles

Calculating the Mass of Zinc Required

Since one mole of zinc produces one mole of hydrogen, we need 0.882 moles of zinc to produce 0.882 moles of hydrogen. The molar mass of zinc (Zn) is approximately 65.38 g/mol. Therefore, the mass of zinc required is:

Mass of Zn = Moles × Molar Mass = 0.882 moles × 65.38 g/mol ≈ 57.69 g

Final Result

In summary, to produce 10 grams of ammonia, you would need approximately 57.69 grams of zinc. This calculation demonstrates the application of the law of constant proportions, as we consistently used the ratios of elements in the reactions to derive the necessary quantities.