REVIEW - Molar Mass, %Comp, Empirical & Molecular Formulas

What is the percent by mass of oxygen in MgO?

• 20%
• 40%
• 50%
• 60%

Which pair has the same empirical formula?

• NaCrO₄ and Na₂Cr₂O₇
• C₂H₄O₂ and C₆H₁₂O₆
• C₃H₆O₃ and C₂H₆O₂
• CH₄ and C₂H₆

A compound consists of 72.2% magnesium and 27.8% nitrogen by mass. What is the empirical formula?

• Mg₄N₃

• MgN₂

• Mg₃N₂

• MgN

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

• Molecular Formula

• Chemical Formula

• Empirical Formula

• Distance Formula

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

• CH₂O
• C₂H₄O₂
• C₄H₈O₄
• C₆H₁₂O₆

Tags

NGSS.MS-PS1-1

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

What is the molar mass of fluorine gas?
(beware!)

• 18.998 g/mol
• 38 g/mol
• 9 g/mol
• 18 g/mol

Tags

NGSS.MS-PS1-1

What is the molar mass of NaOH?

• 40 g/mol
• 38.989 g/mol
• 23.998 g/mol
• 57.004 g/mol

Calculate the molar mass of Ba(C₂H₃O₂)₂

• 255.3 g/mol

• 237.3 g/mol

• 228.3 g/mol

• 196.3 g/mol

Calculate the molar mass for Al(OH)₃

• 78.0 g/mol

• 72 g/mol

• 28 g/mol

• 25 g/mol