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A compound is found to contain 23.3% magnesium, 30.7% sulfur, and 46.0% oxygen. What is the empirical formula of this compound?

Answer 1

#MgSO_3#

We make the assumption that there is 100 grams of substance, as is customary for questions of this nature, and we compute an empirical formula using the percentage elemental compositions.

#"Magnesium"# #=# #(23.3*g)/(24.31*g*mol^-1)# #=# #0.958*mol#

#"Sulfur"# #=# #(30.7*g)/(32.06*g*mol^-1)# #=# #0.958*mol#

#"Oxygen"# #=# #(46.0*g)/(15.999*g*mol^-1)# #=# #2.86*mol#

We divide thru by the smallest molar quantity #(0.958*mol)# to get and empirical formula of #MgSO_3#, magnesium sulfite.

Normally, you would be given the percentages of the metal and sulfur and would have to assume that the balance was oxygen rather than the percentage of oxygen by mass.

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Answer 2

Kai Bowman

MgSO4 is the empirical formula for this compound.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.