What percentage does oxygen make up in the compound #MgSO_4#?

1 Answer
Kayla
Mar 12, 2017

Oxygen makes up #53.16%#

Explanation:

In order to compute the mass percent of oxygen in #MgSO_4# we're going to need two things:

#color(purple)"1: The formula mass of the entire compound"#
#color(purple)"2: The atomic mass of oxygen"#

The formula mass of #MgSO_4# is 120.38 #g/(mol)#
#1(24.31g/(mol)) + 1(32.07g/"mol") +4(16.00 g/"mol")# #= 120.38g/(mol)#

The atomic mass of the oxygen atom is #16.00 g/(mol)#

Now, we have to use the following equation:

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The numerator represents the mass of the desired atom, which is O in our case, and the denominator represents the mass of the entire compound. You just divide the two and multiply by 100 to obtain the percent composition:

#"Mass of O"/("Molar Mass of "MgSO_4") xx100%#

#"(4)16.00 g/mol"/"120.38g/mol"xx100% = 53.16%#

I multiplied the atomic mass of oxygen by 4 because you have to account for all of the oxygen atoms in the formula.

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