Percent Composition

The mass of one mole of a substance is called?

• Molecular mass

• Mole constant

• Molar Mass

• Atomic weight

What is the molar mass of CO₂?

• 12.40 g/mol

• 16.55 g/mol

• 32.21 g/mol

• 44.00 g/mol

What is the percent composition by mass of sulfur (S) in the compound MgSO₄? (mass of MgSO₄ = 120.4 g/mol)

• 20.2%

• 19.9%

• 26.6%

• 28.6%

What is the percent by mass of sodium in NaCl?

• 39%

• 61%

• 35%

• 65%

What is the percent by mass of calcium in CaF₂ (CaF₂ mass = 78 g/mol)?

• 24%

• 49%

• 51%

• 65%

What is the percent composition by mass of magnesium in the compound MgSO₄ (MgSO₄ mass = 120 g/mol)?

• 30%

• 20%

• 46%

• 53%

Magnesium bromide has a chemical formula of MgBr₂. If you look at the total atomic mass of MgBr₂, does magnesium or bromine make up more of the mass?

• bromine

• magnesium

• they are exactly the same

• it is impossible to tell

Lithium phosphide has a chemical formula of Li₃P. If you look at the total atomic mass of Li₃P, does lithium or phosphorus make up more of the mass?

• lithium

• phosphorus

• they are exactly the same

• it is impossible to tell