Chemistry - Calculating Percent (%) Composition

This video tutorial explains percent composition, a concept that describes the percentage of total mass of an element in a compound. It covers the formula for calculating percent composition and provides examples using NaCl, MgF2, and Al2(SO4)3. The tutorial emphasizes the importance of understanding molar mass and demonstrates step-by-step calculations for each example, highlighting the need to account for multiple atoms of an element in a compound.

What is the formula used to calculate percent composition?

• Total mass of the compound multiplied by the mass of the element, divided by 100

• Mass of the element multiplied by the total mass of the compound, divided by 100

• Total mass of the compound divided by the mass of the element, multiplied by 100

• Mass of the element divided by the total mass of the compound, multiplied by 100

In the NaCl example, what is the percent composition of sodium?

• 22.99%

• 50.00%

• 39.34%

• 60.66%

For MgF2, why do we multiply the mass of fluorine by two?

• To simplify the calculation

• Because fluorine is a heavier element

• Because there are two fluorine atoms in the formula

• To balance the equation

In the Al2(SO4)3 example, how many oxygen atoms are there in total?

• 4

• 12

• 16

• 8

What is the molar mass of Al2(SO4)3?

• 342.17 g/mol

• 58.44 g/mol

• 62.31 g/mol

• 100.00 g/mol