Percent Composition and Molar Mass

Mass and Percent Composition

Multiple Choice

What is the Molar Mass of O?

• 16 g/mol

• 8 g/mol

Molar Mass is found on the periodic table!

We should remember at least this much from previous lessons

Multiple Choice

The molar mass of any object always contains 6.022x10²³ particles

• True

• False

To determine the molar mass of a compound we add the molar masses of all atoms involved.

Multiple Choice

What is the molar mass of KNO₃?

• 101 g/mol

• 85 g/mol

• 69 g/mol

• 48 g/mol

Multiple Choice

Name KNO₃

• Potassium Nitrade

• Potasside Nitrate

• Potassium Nitrate

• Potassium Nitrogen

Multiple Choice

In KNO₃, what is oxygen's oxidation number?

• -2

• +2

• -6

• +6

Multiple Choice

What is the Molar mass of Ba(NO₃)₂?

• 261

• 199

• 133

• 71

Mole conversions

• amount of moles x g/mol = g of compound

Multiple Choice

2.5 moles of O₂ has how many grams of O₂?

• 32

• 80

• 2.5

• 6.022x10²³

Multiple Choice

Ibuprofen's chemical formula is C₁₃H₁₈O_2. How many moles are in 33g of iboprofen?

• .16

• .55

• .82

• .32

Multiple Choice

Ibuprofen's chemical formula is C₁₃H₁₈O_2. How many grams of Carbon are in 33g of iboprofen?

• 12g

• 25g

• 13g

• 50g

Percent Composition

• Mass of Element in sample of compound/ Mass of sample of compound

• x100

Multiple Choice

What is the percentage of Copper in Cu₂S?

• 79.8%

• 40%

• .798

• .4

Empirical Formula vs. Molecular Formula

• Empirical is our smallest ratios

• Molecular Formula is the actual number

Multiple Choice

Choose the empirical formula

• Na₂SO₄

• BH₃

• B₂H₆

• C₆H₁₂O₆