Chapter 7 Section 3.2: Molar Mass & Percentage Composition

Chapter 7 Section 3.2: Molar mass & Percentage Composition

​Recall

​Practice problem H on page 240 what is the mass in grams of 2.50 mol of oxygen gas (O₂)

​Practice problem H on page 240 what is the mass in grams of 2.50 mol of oxygen gas (O₂)

​Practice problem H on page 240 what is the mass in grams of 2.50 mol of oxygen gas (O₂)

​Practice problem H on page 240 what is the mass in grams of 2.50 mol of oxygen gas (O₂)

​Sample Problem I on Board

​Why find percentage composition?

​Sample problem J: Find the percentage composition of copper(I) sulfide Cu₂S

• ​First step: find the total molar mass of the compound Cu₂S

  • ​2 Cu= 2 x 63.55

  • ​1 S= 1 x 32.07

​​Sample problem J: Find the percentage composition of copper(I) sulfide Cu₂S