Percent Composition and Molar Mass of NH3

The video tutorial explains how to find the percent composition by mass for NH3 (ammonia). It begins by identifying the molar mass of each element using the periodic table, then calculates the molar mass of the entire compound. The tutorial demonstrates the calculation of percent composition for nitrogen and hydrogen in NH3, using the formula: (mass of element in 1 mole of compound / molar mass of compound) x 100. The video concludes with a note on rounding differences due to periodic table values.

What is the first step in finding the percent composition by mass for NH3?

• Calculate the total mass of NH3.

• Find the molar mass of each element using the periodic table.

• Multiply the atomic masses by 100.

• Determine the number of atoms in NH3.

What is the molar mass of nitrogen used in the calculation for NH3?

• 14.01 grams per mole

• 28.02 grams per mole

• 17.03 grams per mole

• 1.01 grams per mole

How do you calculate the percent composition of nitrogen in NH3?

• Divide the molar mass of nitrogen by the total molar mass of NH3 and multiply by 100.

• Add the molar masses of nitrogen and hydrogen.

• Multiply the molar mass of nitrogen by the number of hydrogen atoms.

• Divide the atomic mass of nitrogen by the atomic mass of hydrogen.

What is the percent composition of nitrogen in NH3?

• 17.79%

• 82.27%

• 14.01%

• 1.01%

What is the atomic mass of hydrogen used in the calculation for NH3?

• 3.03 grams per mole

• 14.01 grams per mole

• 1.01 grams per mole

• 17.03 grams per mole

How is the percent composition of hydrogen in NH3 calculated?

• Multiply the atomic mass of hydrogen by 3, divide by the total molar mass of NH3, and multiply by 100.

• Multiply the atomic mass of hydrogen by the number of nitrogen atoms.

• Divide the total molar mass of NH3 by the atomic mass of hydrogen.

• Add the atomic masses of hydrogen and nitrogen.

What is the percent composition of hydrogen in NH3?

• 82.27%

• 17.79%

• 1.01%

• 14.01%

Why might the calculated percent compositions be slightly off?

• Due to incorrect multiplication.

• Because of rounding to two decimal places.

• Because the periodic table is outdated.

• Due to incorrect atomic masses.