[coco77]

Can Al(H₂O)₆K(H₂O)₆(SO₄)₂ be written AlH₂₄KO₂₀S₂? Or AlK(SO₄)₂(H₂O)₁₂

I don't think it can be written the second way because the formula doesn't explicitly tell you that the H's and O's make up mostly water...

[billnotgatez]

What is the name of the compound you are depicting?
Is it Alum (hydrated potassium aluminium sulfate)?

Can you format this properly with subscript as per forum rules?

[coco77]

What is the name of the compound you are depicting

alum. formal designation "aluminum potassium sulfate dodecahydrate"

Al(H₂O)₆K(H₂O)₆(SO₄)₂ be written AlH₂₄KO₂₀S₂? Or AlK(SO₄)₂(H₂O)₁₂

[billnotgatez]

When you write a compound that has hydrate in it do you need another symbol between the water and the non water part

[Borek]

In a way all formulae that you wrote are acceptable. Which one you will use depends on what you are trying to tell.

AlK(SO₄)₂(H₂O)₁₂

As Bill signaled, the best way of writing it is AlK(SO₄)₂·12H₂O

[coco77]

In a way all formulae that you wrote are acceptable. Which one you will use depends on what you are trying to tell.

So...the first one tells us that structurally the waters surround Al and K. In what scenarios would the other 2 be useful?

[billnotgatez]

The first time you wrote the formula you used regular number rather than subscript
In practice you should have wrote it out correctly in your second post rather than editing your first post.
This makes for more clarity for reading the post.
I post this here so if someone reads these entries they will not be confused, not to chide you.

the part of the formula

·12H2O

gives you a better idea that you have a hydrate, which is useful when depicting chemical reactions.

[coco77]

The first time you wrote the formula you used regular number rather than subscript
In practice you should have wrote it out correctly in your second post rather than editing your first post.
This makes for more clarity for reading the post.
I post this here so if someone reads these entries they will not be confused, not to chide you.

the part of the formula

·12H2O

gives you a better idea that you have a hydrate, which is useful when depicting chemical reactions.

Sorry about that! Thanks!

[billnotgatez]

By the way
I can not find where anyone writes the empirical formula different from the molecular formula.

[coco77]

The question is from my lab notebook (Postma) and it seems to be more of a "challenge yourself by pondering this" question.