Chemical Composition and Atomic Mass

This video tutorial explains how to find the percent composition by mass for each element in aluminum nitrate (Al(NO3)3). It covers calculating the molar mass of the compound and then determining the percent composition for aluminum, nitrogen, and oxygen. The video concludes with a summary of the calculations and results.

What is the chemical formula for aluminum nitrate?

• Al2(NO3)3

• Al2(NO2)3

• Al(NO3)3

• Al(NO2)3

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

• Determine the atomic number

• Find the number of moles

• Calculate the molar mass of the compound

• Identify the elements in the compound

What is the atomic mass of aluminum used in the calculation?

• 26.98 grams per mole

• 14.01 grams per mole

• 16.00 grams per mole

• 28.09 grams per mole

How many aluminum atoms are present in one formula unit of Al(NO3)3?

• Four

• Three

• Two

• One

What is the percent composition of aluminum in Al(NO3)3?

• 15.00%

• 12.67%

• 19.73%

• 67.60%

What is the atomic mass of nitrogen used in the calculation?

• 14.01 grams per mole

• 16.00 grams per mole

• 26.98 grams per mole

• 12.01 grams per mole

How many nitrogen atoms are present in one formula unit of Al(NO3)3?

• Three

• Twelve

• Six

• Nine

What is the percent composition of nitrogen in Al(NO3)3?

• 67.60%

• 19.73%

• 12.67%

• 25.00%

What is the atomic mass of oxygen used in the calculation?

• 12.01 grams per mole

• 26.98 grams per mole

• 14.01 grams per mole

• 16.00 grams per mole

What should the total percent composition of all elements in a compound add up to?

• 100%

• 90%

• 110%

• 95%