QuickCheck: Percent Composition

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%

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

Percent composition of an element is found by:

• mass of element divided by total mass of compound, times 100

• mass of compound divided by mass of element, times 100

• mass of first element one divided by mass of second element, times 100

• mass of compound times mass of element, times 100

The chemical compound myristicin is found in many spices, such as nutmeg. If a 0.500 g sample of myristicin contains 0.343 g of carbon, what is the mass percent of carbon?

• 68.6% carbon

• 1.46% carbon

• 15.7% carbon

• 31.4% carbon