Percent Composition Empirical and Molecular Formulas

What is the percent by mass of fluorine in CaF₂ (gram-formula mass = 78 g/mol)?

• 24%

• 49%

• 51%

• 65%

Tags

NGSS.HS-PS1-7

A formula with the lowest whole # ratio of elements in a compound is called

• Molecular Formula

• Chemical Formula

• Empirical Formula 

• Distance Formula

A chemical formula that shows the actual # and kinds of atoms present in one molecule of a compound is called_________

• ionic formula

• covalent formula

• empirical formula

• molecular formula

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)

Which pair has the same empirical formula?

• NaCrO₄ and Na₂Cr₂O₇

• C₂H₄O₂ and C₆H₁₂O₆

• C₃H₆O₃ and C₂H₆O₂

• CH₄ and C₂H₆

Tags

NGSS.HS-PS1-7

What is the empirical formula of a molecule containing 18.7% of Lithium, 16.3% of Carbon and 65.0% of oxygen?

• CO₂Li₃

• Li₂CO₃

• Li₃CO₂

• LiCO₅

Tags

NGSS.HS-PS1-7

What is the empirical formula if you have 81.82% carbon and 18.18% hydrogen?

• C3H8

• CH4

• C2H2

• C4H10

What is the empirical formula for N₂S₃?

• NS

• N₃S₂

• N₂S₃

• N₁S_1.5

Tags

NGSS.MS-PS1-1

Phenyl magnesium bromide is used as a reagent in organic synthesis. Determine its molecular formula if its molar mass is 181.31 g/mol and it contains 39.75% C, 2.78% H, 13.41% Mg, and 44.07% Br (these are in the correct order).

• C₁₂H₁₀Mg₂Br₂

• CHMgBr

• C₆H₅MgBr

• C₃H_2.5MgBr

• A) 47%

• B) 53%

• C) 94%

• D) 68%