Percent Composition, Empirical and Molecular Formula

The molecular and empirical formula of a compound are __________ the same.

• always

• sometimes

• never

• one and

Chloroform, a toxic substance that may cause severe liver, kidney, and heart damage, has the percent composition by mass of this compound is 10.06% carbon, 0.84% hydrogen, and 89.09% chlorine. What is its molar mass in g/mol?

• 124.42

• 121.39

• 119.37 

• 74.51

Chloroform, a toxic substance that may cause severe liver, kidney, and heart damage, has the percent composition by mass of this compound is 10.06% carbon, 0.84% hydrogen, and 89.09% chlorine. If a compound which shares the same empirical formula as chloroform is known to have a molar mass of 223.53g/mol, what is the compound’s mole ratio with chloroform?

• 2

• 3

• 4

• 5

Tags

NGSS.HS-PS1-7

Do the diagrams have the same molecular formula?

• Yes

• No

Tags

NGSS.MS-PS1-1

Which of the following is NOT needed to calculate percent mass composition?

• Molar Mass of each specific element

• Molar Mass of Compound

• Avogadro's Number

• Division

Find the percentage composition of Mg in Mg₃(PO₄)₂.

• 27.48% Mg

• 43.11% Mg

• 16.00% Mg

• 12.63% Mg

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

• Molecular Formula

• Chemical Formula

• Empirical Formula 

• Distance Formula

A compound is made up of 40.05% S and 59.95% O by mass. Find the empirical formula for these elements.

• SO

• SO₂

• SO₃

• SO₄

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

• Mg₄N₃

• MgN₂

• Mg₃N₂ 

• MgN

What is the empirical formula of a compound with 88.80% copper and 11.20% oxygen by mass?

• Cu₃O₈

• CuO₄

• Cu₂O

• Cu₄O₁₀

Tags

NGSS.HS-PS1-7