Percent Composition - 2022

What percentage of the total atomic mass of carbon monoxide is composed of carbon?

• 29%

• 43%

• 57%

• 73%

If you look at the total atomic mass of lithium phosphide, does lithium or phosphorus make up more of the mass?

• lithium

• phosphorus

• they are exactly the same

• it is impossible to tell

What is the percentage of oxygen in carbon dioxide?

• 27.3%

• 72.7%

• 30%

• 70%

Which element in the compound potassium cyanide has a percent composition of 60.97%?

• K

• C

• N

• None of the above

***BONUS***An 8 oz cup of coffee can contain up to 0.200 g of caffeine. If in this caffeine there is 0.099 g carbon, 0.010 g hydrogen, 0.058 g nitrogen, and 0.033 g oxygen, what is the mass percent of each element in caffeine?

• 49.5% carbon,

  5% hydrogen,

  29% nitrogen,

  16.5% oxygen

• 9.9% carbon

  10% hydrogen

  58% nitrogen

  33% oxygen

• 19.8% carbon,

  5% hydrogen

  29% nitrogen

  46.2% oxygen

• 2% carbon

  20% hydrogen

  29% nitrogen

  6% oxygen

The molecule vanillin is responsible for the flavor of vanilla and is made of carbon, hydrogen, and oxygen. If vanillin is 63.1% carbon and 5.4% hydrogen by mass, what is the percent oxygen in this compound?

• 31.6%

• 68.4%

• 100%

• 57.7%