Percent Composition and Molar Mass

This video tutorial explains how to calculate the percent composition of each element in glucose (C6H12O6). It begins by determining the molar mass of the entire compound and then calculates the percent composition for carbon, hydrogen, and oxygen. The tutorial provides step-by-step instructions for each element, including multiplying the atomic mass by the number of atoms and dividing by the compound's molar mass. The video concludes with a brief explanation of rounding differences due to periodic table values.

What is the chemical formula for glucose?

• C7H14O7

• C6H6O6

• C5H10O5

• C6H12O6

What is the molar mass of glucose in grams per mole?

• 200.20

• 160.16

• 150.15

• 180.18

How do you calculate the percent composition of an element in a compound?

• Divide the atomic mass by the number of atoms, multiply by the molar mass of the compound, and multiply by 100.

• Multiply the atomic mass by the molar mass of the compound, divide by the number of atoms, and multiply by 100.

• Multiply the atomic mass by the number of atoms, divide by the molar mass of the compound, and multiply by 100.

• Add the atomic mass to the number of atoms, divide by the molar mass of the compound, and multiply by 100.

What is the percent composition of carbon in glucose?

• 30.00%

• 60.00%

• 50.00%

• 40.00%

How many carbon atoms are present in a glucose molecule?

• 6

• 10

• 8

• 12

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

• 1.00

• 1.01

• 2.02

• 1.10

What is the percent composition of hydrogen in glucose?

• 6.73%

• 7.73%

• 5.73%

• 8.73%

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

• 17.00

• 18.00

• 15.99

• 16.00

What is the percent composition of oxygen in glucose?

• 52%

• 55%

• 50%

• 53%

Why might the total percent composition not add up to exactly 100%?

• Because of measurement errors.

• Due to the presence of impurities.

• Because of incorrect calculations.

• Due to rounding of atomic masses to two decimal points.