Moles and Percent Composition

Match the following terms

• Empirical Formula

• unit for molar mass

• g/mol

• % by mass of each element in a compound

• Molar Mass

• the mass, in grams, of 1 mol of any substance

• Percent Composition

• simplest whole # ratio of atoms of elements in a compound

Match the compound to its molar mass

• CaCO₃

• 44.01 g/mol

• H₂O

• 18.02 g/mol

• CO₂

• 100.09 g/mol

Place the molecules in order of smallest molar mass to greatest molar mass.

• Br₂

• I₂

• F₂

• H₂

• N₂

What is the % composition of CO₂?

• %_{comp C} = 27.3%

  %_{comp O} = 72.7%

• %_{comp C} = 37.5%

  %_{comp O} = 62.5%

• %_{comp C} = 33.3%

  %_{comp O} = 66.6%

• %_{comp C} = 63.6%

  %_{comp O} = 36.4%

An unknown compound has percent compositions of 72.2% Magnesium and 27.8% Nitrogen. What is the empirical formula?

• Mg₃N₂

• Mg₂N₃

• MgN

• Mg₃N₅

The element with a molar mass of 78.97 g/mol is (a)   (name).

• Selenium
• Oxygen
• Carbon
• Nitrogen

The empirical formula of P₄O₁₀ is -

• PO

• P₂O₅

• P₄O₁₀

• PO₃

Determine the molar mass of H₂; and then calculate the number of moles in 45.0 grams of H₂.

• 1.01g/mol; 1.22x10²⁴ mol

• 2.02g/mol; 22.3 mol

• 1.01g/mol; 44.6 mol

• 2.02g/mol; 1.22x10²⁴ mol

• 3.3x10²³ particles

• 55 particles

• 5 particles

• 6.0x10²³ particles

Tags

NGSS.HS-PS1-7

Calculate the mass of a substance that contains 2 mol of H₂. 

• 1.01g

• 4.04g

• 1.02g

• 2.01g