Question #ef14a

1 Answer
Jun 8, 2015




A compound's empirical formula tells you what the smallest mole ratio that exists between the atoms that form that compound is.

Your compound's empirical formula is #C_2H_4O#, which means that, regardless of how many carbon atoms the actual compound has, it will have 2 times more hydrogen atoms and 4 times fewer oxygen atoms.

To determine exactly how many atoms your compound contains, you can use its molar mass, which tells you what the mass of 1 mole of a substance is.

In your case, the molar mass is equal to 88 g/mol. This means that, if you add the molar masses of each atom that makes up your compound, you'll end up with 88 g/mol.

You know that your compound contains at least 2 carbons, 4 hydrogens, and 1 oxygen. Use their molar masses to get

#(C_2H_4O)_color(blue)(n) = "88 g/mol"#

#(2 * 12.0 + 4 * 1.01 + 1 * 16.0)cancel("g/mol") * color(blue)(n) = 88cancel("g/mol")#

#44.04 * color(blue)(n) = 88 => color(blue)(n) = 88/44.04 = 1.998 ~=2#

Thus, your compound's molecular formula, which contains all the atoms present in the molecule, will be

#(C_2H_4O)_2 => C_4H_8O_2#