Exam questions...

Already a couple questions...

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Is the empirical formula just the smallest whole number ratio? What if it came out C=1.5 H=2.5 O=3 or something like that? Is that still the empirical formula? or would the empirical formula be C=3 H=5 O=6, and then work from there to get your molecular formulas?!

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Yes, the empirical formula is the smallest whole number ratio, so in your example the most correct way to report the empirical formula would be C₃H₅O₆. The molecular formula would be some multiple of that and you'd have to be given more information in the problem to determine the correct molecular formula.

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For percent composition questions with multiple elements, will be expected to have the elements in the correct order in the final answer? For example: KMnO₄ instead of say MnKO₄....Or will the main concern be that we achieved the correct amount of each element?

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Quite a few people have asked me about this and in general the order doesn't matter. The only place your should pay attention to the order and groupings is in the formulas of ionic compounds and polyatomic ions. When writing the formula for an ionic compound it is usually best accepted practice to list the cation first, followed by the anion, and you should always write polyatomic ions as their common formula is written. In your example, since permanganate is a polyatomic ion, it should always be written together as "MnO₄^-". Since this is an ionic compound, the cation {potassium ion} should also be written first, so this should be written KMnO₄. That's not a result of it being a percent composition problem, that's the naming convention for ionic compounds.

If you have other questions, let me know, I'll post answers to the blog ASAP.