November 23, 2024, 11:38:23 PM
Forum Rules: Read This Before Posting


« previous next »
Pages: [1]   Go Down

Topic: Different ways to write a hydrate formula?  (Read 3815 times)

0 Members and 3 Guests are viewing this topic.

Offline coco77

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
Different ways to write a hydrate formula?
« on: March 03, 2013, 04:53:35 PM »
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...
« Last Edit: March 03, 2013, 06:01:03 PM by coco77 »
Logged

Offline billnotgatez

  • Global Moderator
  • Sr. Member
  • ***
  • Posts: 4431
  • Mole Snacks: +224/-62
  • Gender: Male
Re: Different ways to write a hydrate formula?
« Reply #1 on: March 03, 2013, 05:50:18 PM »
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?
Logged

Offline coco77

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
Re: Different ways to write a hydrate formula?
« Reply #2 on: March 03, 2013, 05:56:44 PM »
Quote from: billnotgatez on March 03, 2013, 05:50:18 PM
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
Logged

Offline billnotgatez

  • Global Moderator
  • Sr. Member
  • ***
  • Posts: 4431
  • Mole Snacks: +224/-62
  • Gender: Male
Re: Different ways to write a hydrate formula?
« Reply #3 on: March 03, 2013, 06:05:09 PM »
When you write a compound that has hydrate in it do you need another symbol between the water and the non water part
Logged

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27858
  • Mole Snacks: +1813/-412
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Different ways to write a hydrate formula?
« Reply #4 on: March 03, 2013, 06:07:10 PM »
In a way all formulae that you wrote are acceptable. Which one you will use depends on what you are trying to tell.

Quote from: coco77 on March 03, 2013, 05:56:44 PM
AlK(SO4)2(H2O)12

As Bill signaled, the best way of writing it is AlK(SO4)2·12H2O
Logged
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline coco77

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
Re: Different ways to write a hydrate formula?
« Reply #5 on: March 03, 2013, 06:15:11 PM »
Quote from: Borek on March 03, 2013, 06:07:10 PM
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?
Logged

Offline billnotgatez

  • Global Moderator
  • Sr. Member
  • ***
  • Posts: 4431
  • Mole Snacks: +224/-62
  • Gender: Male
Re: Different ways to write a hydrate formula?
« Reply #6 on: March 03, 2013, 06:16:56 PM »
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
Quote
·12H2O
gives you a better idea that you have a hydrate, which is useful when depicting chemical reactions.
Logged

Offline coco77

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
Re: Different ways to write a hydrate formula?
« Reply #7 on: March 03, 2013, 06:18:44 PM »
Quote from: billnotgatez on March 03, 2013, 06:16:56 PM
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
Quote
·12H2O
gives you a better idea that you have a hydrate, which is useful when depicting chemical reactions.

Sorry about that! Thanks!
Logged

Offline billnotgatez

  • Global Moderator
  • Sr. Member
  • ***
  • Posts: 4431
  • Mole Snacks: +224/-62
  • Gender: Male
Re: Different ways to write a hydrate formula?
« Reply #8 on: March 03, 2013, 06:32:22 PM »
By the way
I can not find where anyone writes the empirical formula different from the molecular formula.
Logged

Offline coco77

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
Re: Different ways to write a hydrate formula?
« Reply #9 on: March 03, 2013, 06:34:46 PM »
The question is from my lab notebook (Postma) and it seems to be more of a "challenge yourself by pondering this" question.
Logged
Pages: [1]   Go Up
« previous next »
Sponsored Links