Chemical Composition (Moles) Quiz

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 of Cu₂O.

• 37 g/mol

• 45 g/mol

• 79.5 g/mol

• 143 g/mol

What is the percent by mass of oxygen in MgO?

• 20%
• 40%
• 50%
• 60%

What is the percent by mass of magnesium in MgO?

• 20%
• 40%
• 50%
• 60%

What is the percent composition by mass of sulfur in the compound MgSO₄ (gram formula mass = 120 g/mol)?

• 20%
• 27%
• 46%
• 53%

What is the definition for Avogadro's number?

• number of grams per one mole of a substance

• whole number ratio that is a multiple of a chemical formula

• simplest, whole number ratio of a chemical formula

• 6.02 x 10²³ particles per one mole of a substance

How many moles are present in 32.3 grams of carbon dioxide (CO₂)?

• 44.01 moles
• 1421.52 moles
• 32.3 moles
• 0.73 moles

How many moles are in 20 grams of Ca (Calcium)?

• 0.5 
• 1
• 3
• 20

How many molecules are in 2.5 mol of NaCl?

• 1.51x10²³
• 146
• 4.15
• 1.51x10²⁴

What is the mass of 0.89 mol of CaCl₂?

• 111 grams
• 0.008 grams
• 98.9 grams
• none of the choices