[beestree]

Hello, I am having a lot of trouble with this homework question and am hoping someone will help. I have been able to get through several other EF/ MF problems with no trouble, so not sure why this one is giving me trouble.  The answer I came up with may be correct, but I have a sneaking suspicion it's not!! Please find the question and the work I've done below.  Any help would be greatly appreciated!!
Thanks!

Here is the question:

Complicated chemical reactions occur at hot springs on the ocean floor.  One compound from such a hot springs consists of Mg, Si, and O.  From a 0.301 g sample the Mg is recovered as 0.104 g of magnesium oxide; H is recovered as 23.1 mg of water; and Si is recovered as 0.155 g of silicon dioxide.  What is the simplest formula of this compound.  What is the molecular formula of the compound is the molar mass is 117.41 g/mol.

Here is what I have done…….

0.104 g MgO x 1 mol MgO/40.3 g MgO x 1 mol Mg/1mol MgO x 24.31 g Mg/1 mol Mg = .0627 g Mg

0.155 g SiO2 x 1 mol SiO2 /60.07 g SiO2 x 1mol Si/1 mol SiO2 x 28.09 g Si/1 mol Si =.0725 g Si

0.0231 g H2O x 1 mole H2O / 18.01 g H2O x 2 mol H/1 mol H2O x 1.01 g H/1 mol H = .0026 g H

g O = 0.1632

To find EF:

.0627 g Mg/24.31 g Mg = .00258 mol Mg/.00258 = 1 Mg
.0026 g H/1.01 g H = .00258 mol H/.00258 = 1 H
.0725 g Si/28.09 g Si = .00258 mol Si/.00258 = 1 Si
.1632 g O/15.99 g O = .01021 mol O/.00258 = 3.95 O

So is the EF MgSiHO₄??

To find MF

117.41/101.38 = 1.16 g/mol

Here is were I am totally confused and convinced that I did something wrong. Does this mean that in this case the MF is the same as the EF? 
Thanks in advance for any help.

[Borek]

IMHO something is wrong - not with the way you are doing it, but with the question. Note that H is not listed as the compound component, note that the difference between given molar mass and found molar mass is almost exactly 16 - which is 1 oxygen. I doubt it is a concidence.

[beestree]

Hello,
OOOPS! Sorry, I forgot to type in the H in the question (something is wrong with the typist!).  Thanks for your reply Borek.  I turned in the homework this morning, so we'll see how it goes.
Thanks again.