To calculate the number of moles of nitrogen (N2) required to produce 55.5 grams of ammonia (NH3), we need to use the balanced chemical equation and the molar masses of the reactants and products.

The balanced chemical equation is:

N2 + 3H2 -> 2NH3

First, we need to convert the mass of ammonia to moles using its molar mass. The molar mass of NH3 is 14.01 grams/mole (14 grams of nitrogen and 3 grams of hydrogen).

Moles of NH3 = Mass of NH3 / Molar mass of NH3

Moles of NH3 = 55.5 grams / 17.04 grams/mole

Moles of NH3 = 3.26 moles

According to the balanced chemical equation, 1 mole of N2 is required to produce 2 moles of NH3. So, we can calculate the number of moles of N2 needed:

Moles of N2 = Moles of NH3 / 2

Moles of N2 = 3.26 moles / 2

Moles of N2 = 1.63 moles

Now, we can convert moles of N2 back to grams using its molar mass. The molar mass of N2 is 28.02 grams/mole (2 x 14 grams of nitrogen).

Mass of N2 = Moles of N2 * Molar mass of N2

Mass of N2 = 1.63 moles * 28.02 grams/mole

Mass of N2 = 45.68 grams

Therefore, 45.68 grams of nitrogen (N2) are required to produce 55.5 grams of ammonia (NH3).