Calculating Molecular Formulas

What is the percent by mass of magnesium in MgO?

• 20%
• 40%
• 50%
• 60%

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

• 20%
• 27%
• 46%
• 53%

What is the empirical formula if you have 88.80% copper and 11.20% oxygen?

• Cu₃O₈
• CuO₄
• Cu₂O
• Cu₄O₁₀

What is the empirical formula if you have 36.84% nitrogen and 63.16% oxygen?

• NO
• N₂O₃
• N₂O₄
• N₂O₅

What is the molecular formula if the empirical formula is CH₂O and the molecular molar mass is 180.18?

• CH₂O
• C₂H₄O₂
• C₄H₈O₄
• C₆H₁₂O₆

What is the molecular formula for a compound with the empirical formula: K₂SO₄ and a molecular mass of 696g.

• K₂SO₄ 
• K₈SO₁₆
• K₈S₄O₈ 
• K₈S₄O₁₆ 

EF = CF₂ 
Molecular formula mass = 192
MF =

• C₄F₈
• C₄F
• CF₈
• C₂F₄

?

• CH₄N₂0
• CH₄N0
• CHN₂0
• C₂H₄N₂0₈

Tags

NGSS.HS-LS1-6

When calculating the EF the mole ratio is given as follows:
H₁O_{3.5
What will the EF be?}

• H₁O_3.5
• HO_3.5
• HO₄
• H₂O₇

Tags

NGSS.HS-PS1-7

20% Ca, 80 Br. EF=

• CaBr
• CaBr₂
• Ca₂Br
• Ca₂Br₂