Percent Composition and Atomic Counts

The video tutorial explains how to calculate the percent composition by mass of each element in sodium phosphate (Na3PO4). It begins with an introduction to the concept of percent composition. The tutorial then details the calculation process for sodium, phosphorus, and oxygen, using their respective molar masses and the total molar mass of Na3PO4. Each element's percent composition is calculated by multiplying the molar mass by the number of atoms, dividing by the compound's molar mass, and multiplying by 100 to convert to a percentage. The video concludes by summarizing the calculations and ensuring the percentages add up to approximately 100%.

What is the primary focus when calculating percent composition by mass?

• Identifying the elements in a compound

• Determining the volume of the compound

• Calculating the density of the compound

• Finding the boiling point of the compound

How do you calculate the percent composition by mass of sodium in sodium phosphate?

• Divide the atomic mass of sodium by the total mass of the compound

• Multiply the molar mass of sodium by the number of sodium atoms, then divide by the molar mass of sodium phosphate

• Subtract the mass of sodium from the total mass of the compound

• Add the atomic masses of all elements in the compound

What is the molar mass of sodium used in the calculation?

• 15.99 grams per mole

• 22.99 grams per mole

• 30.97 grams per mole

• 39.10 grams per mole

How many phosphorus atoms are present in sodium phosphate?

• Three

• Four

• Two

• One

What is the percent composition by mass of phosphorus in sodium phosphate?

• 25.00%

• 39.04%

• 18.87%

• 42.07%

How many oxygen atoms are present in sodium phosphate?

• Four

• Two

• Five

• Three

What should the total percent composition by mass of all elements in sodium phosphate add up to?

• 150%

• 100%

• 75%

• 50%