Moles, Percent Composition, Empirical and Molecular Formulas

Which pair has the same empirical formula?

• NaCrO₄ and Na₂Cr₂O₇

• C₂H₄O₂ and C₆H₁₂O₆

• C₃H₆O₃ and C₂H₆O₂

• CH₄ and C₂H₆

What is the chemical formula for iron(III) chloride hexahydrate?

• FeCl3·6H2O

• FeCl3·3H2O

• Fe2Cl6·6H2O

• Fe3Cl6·H12O3

How many Carbon atoms are in one mole of Carbon?

• 6.02 x 10²³

• 1

• 12

• not enough information

How many moles are in 3.01 x 10²² atoms of magnesium?

• 0.05 moles

• 1.81 x 10⁴⁶ moles

• 5.00 x 10²¹ moles

• 5 moles

What is the mass of 0.89 mol of CaCl₂?

• 111 grams

• 0.008 grams

• 98.9 grams

• none of the choices

Avogadro’s number is:

• 6.02 x 10²²

• 6

• 6.02 x 10²³

• 3.01 x 10²³

Tags

NGSS.HS-PS1-7

What is the percent composition by mass of magnesium in the compound MgSO₄

• 20%

• 27%

• 46%

• 53%

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

• Cu₃O₈

• CuO₄

• Cu₂O

• Cu₄O₁₀

Tags

NGSS.HS-PS1-1

What is the empirical formula for the following molecular formula: C₆H₁₄

• C₆H₁₄

• C₃H₇

• CH₂

• CH₃

What is the molecular formula if the empirical formula is C₂H₅ and the molecular molar mass is 58.14 g/mol?

• C₂H₅

• C₄H₁₀

• C₁H_2.5

• C₄H₈