Molar Mass and Percent Composition

What is the percent by mass of oxygen in MgO?

MgO: 40g/mol

• 20%

• 40%

• 50%

• 60%

What is the percent by mass of magnesium in MgO?

MgO: 40g/mol

• 20%

• 40%

• 50%

• 60%

What is the percent by mass of sodium in NaCl?

NaCl: 58.45g/mol

• 39%

• 61%

• 35%

• 65%

What is the percent by mass of chlorine in NaCl?

NaCl: 58.45g/mol

• 39%

• 61%

• 35%

• 65%

What is the percent by mass of fluorine in CaF₂

(CaF₂ = 78 g/mol)?

• 24%

• 49%

• 51%

• 65%

What is the percent by mass of calcium in CaF₂

(CaF₂ = 78 g/mol)?

• 24%

• 49%

• 51%

• 65%

In which compound is the percent composition by mass of Cl equal to 42%?

• HClO (gram formula mass = 52 g/mol)
• HClO₂ (gram formula mass = 68 g/mol)
• HClO₃ (gram formula mass = 84 g/mol)
• HClO₄ (gram formula mass = 100 g/mol)

The molar mass of an element is equal to its...

• Atomic mass
• Atomic number
• Oxidation number
• Valence electrons

The mass of one mole of substance is called...

• molecular mass
• mole constant
• molar mass
• atomic weight

What is the molar mass of sodium?

• 11
• 23
• 45.98
• 3