Final answer:
The percent composition of nitrogen in ammonia (NH₃) is 82.24%, calculated by dividing the atomic mass of nitrogen (14.01 amu) by the formula mass of NH₃ (17.034 amu) and multiplying by 100.
Step-by-step explanation:
To calculate the percent composition of nitrogen in ammonia (NH₃), we start by determining its formula mass. Ammonia consists of one nitrogen atom with a mass of 14.01 atomic mass units (amu) and three hydrogen atoms with a combined mass of about 3.024 amu (1.008 amu each).
The formula mass of ammonia is the sum of the masses of its atoms, which is (14.01 amu + 3.024 amu) = 17.034 amu. The percent of nitrogen in ammonia is then calculated by taking the mass of the nitrogen atom and dividing it by the formula mass of ammonia, and then multiplying by 100 to get the percentage:
Percent of N in NH₃ = (14.01 amu / 17.034 amu) × 100 = 82.24%
Therefore, nitrogen makes up 82.24% of the mass of an ammonia molecule.