Question #ce7a4

1 Answer
Stefan V.
Apr 30, 2016

#"C"_9"H"_8"O"_4#

Explanation:

As it turns out, the problem already provides you with the molecular formula and the empirical formula of aspirin, or acetylsalicyclic acid, #"C"_9"H"_8"O"_4#.

http://www.123rf.com/photo_18083157_structural-model-of-aspirin-molecule.html

A compound's molecular formula tells you the exact number of atoms of each constituent element present in one molecule of this compound. In your case, one molecule of aspirin contains

  • nine atoms of carbon, shown here in black
  • eight atoms of hydrogen, shown here in light gray
  • four atoms of oxygen, shown here in red

This is why the compound's molecular formula is #"C"_9"H"_8"O"_4#.

Now, the empirical formula tells you the smallest whole number ratio that exists between a compound's constituent elements.

In this case, a #9:8:4# ratio between carbon, hydrogen, and oxygen is already the smallest than can be expressed using whole numbers, which means that #"C"_9"H"_8"O"_4# is also the empirical formula of aspirin.

#color(green)(|bar(ul(color(white)(a/a)color(black)("C"_9"H"_8"O"_4)color(white)(a/a)|))) -># empirical and molecular formula

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