Mini Unit: % comp, Empirical & Molecular Formula Practice Quiz

What is percent composition?

• The percent by mass of an element in a compound.

• The percent by number of atoms of an element in a compound.

• The mole ratio of an element in a compound.

• The mole ratio between the salt and water in a hydrate.

What is the percent composition of copper in copper(II) bromide?

• 28.45%

• 33.33%

• 50.00%

• 44.30%

The percent composition of sulfur in aluminum sulfide is %. (Provide answer to 2 decimal places)

(a)  

A chemist determines that 1.26 g of iron reacts with 0.54 g of oxygen to form rust. The percent composition of each element in the product is: ​ (a)   % iron and ​ (b)   % oxygen.

• 70.0
• 30.0
• 3.4
• 2.23
• 42.9
• 57.1

What is the empirical formula for the following:
Pb₅Cr₅O₂₀

• Pb₂Cr₂O₁₀
• PbCr₂O₇
• Pb₉Cr₄O₂
• PbCrO₄

Tags

NGSS.HS-PS1-7

Which element has a percentage of 39.03% in the compound sodium phosphate, Na₃PO₄

• Na

• P

• O

• None of the above

Tags

NGSS.MS-PS1-1

A chemical formula that shows the actual # and kinds of atoms present in one molecule of a compound is called_________

• ionic formula

• covalent formula

• empirical formula

• molecular formula

What is the empirical formula for C₄H₆?

• CH

• CH₃

• C₂H₃

• C₄H₆

Tags

NGSS.HS-PS1-7

Which pair has the same empirical formula?

• NaCrO₄ and Na₂Cr₂O₇

• C₂H₄O₂ and C₆H₁₂O₆

• C₃H₆O₃ and C₂H₆O₂

• CH₄ and C₂H₆

Tags

NGSS.HS-PS1-7

What is the empirical formula for N₂S₃?

• NS

• N₃S₂

• N₂S₃

Tags

NGSS.MS-PS1-1