Writing a Formula Based Off of Compound Name (E.9)

[Isaac Wen]

Hi!

I was working on E.9 from the fundamentals section and was just wondering if there's any way to remember how to convert compound names to their empirical formulas. The question asks you to write magnesium sulfate heptahydrate (Epsom salt) as a formula, but I unfortunately don't know how to do that without searching it up. Namely, is there a way I could infer what heptahydrate's formula is solely based on the information given? Or is this something I just have to memorize?

[Sydney Lam_2I]

Hi!

Unfortunately you'll have you remember the ions to create the compound which will be part of the magnesium sulfate. For the heptahydrate, the prefix will always be the number of moles of H2O with the compound. Hope this helps!

[Madeline Louie 1I]

I was wondering the same thing. When it comes to exams will we need to convert the written out names of molecules and polyatomic ions to their formula ourselves or will it be given in the question?

[Sharon Kim 2A]

I usually write the magnesium sulfate formula as you would and write out how many H20 there are by the prefixes. Same goes for all other formulas that have hydrate next to it.

[Olivia Smith 2E]

I asked my TA and she said that we did not need to be very strong at nomenclature! All of the needed equations and chemical formulas will be given or can be derived from the problem without the need to know all of the ions. Although it might be smart to just brush up on that stuff. I know you can find good guides to all things nomenclature on khan academy as well as just looking up nomenclature tables online!

[FionaHunter21]

So are we supposed to know how to write a formula for a given molecule based on its prefixes and ending? Should I review the difference between endings such as -ide vs -ate, and things like that?

[Mackenzie Stockton 2H]

I also had this question. Fundamentals D (Nomenclature), which is part of the optional reading, is all about naming compounds and all the rules. It was very helpful and I would recommend looking at sections 1-4 if you're having difficulty because it really cleared it up for me!