The Mole (18/19)

Name the following ionic compound: MgSO₄*7H₂O

• magnesium sulfate * hexahydarte
• magnesium sulfate hexahydarte
• magnesium sulfate heptahydrate
• magnesium sulfate* heptahydrate

Na₂CO₃ · 10H₂O is known as sodium sulfate ______

• Hydroxide
• Hydrate
• Decahydrate
• None of the above

Name the following hydrate:  NaCl * 5H₂O

• sodium chloride 
• sodium monochloride pentahydrate
• sodium chloride pentahydrate
• pentahydrate

Magnesium pentahydrate 

• MgCO₃ · 5H₂O
• MgCO₃ · 4H₂O
• MgCO₃ · 6H₂O
• MgCO₃ · 1H₂O

What is the percent by mass of magnesium in MgO?

• 20%
• 40%
• 50%
• 60%

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

• Mass of specific element
• Molar Mass
• Avogadro's Number
• Division

What is the percent composition of sulfur compound that contains 20.8 g carbon and 54.4 g sulfur?

• 42.9 % carbon; 57.1%sulfur
• 27.7% carbon; 72.3 % sulfur
• 40.8 % carbon; 54.4 % sulfur
• 54.4 % carbon; 40.8% sulfur

An empirical formula:

• is a formula that calculates the coefficients of a compound in a balanced equation.
• is the simplest whole-number ratio of moles of elements in the compound.

What is the empirical formula of the following molecular formula:  C₃H₆

• C₃H₆
• CH₂
• C₂H₄
• CH₃

You are given the following percentages: 40.05% S and 59.95% O. Find the empirical formula for these elements. (keep two decimal places throughout calculations)

• SO
• SO₂
• SO₃
• SO₄