Previous in Forum: Where Can I find for High Quality (Free) Online Scientific Journals?   Next in Forum: Plastisol Ink
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
9 comments
Rate Comments: Nested
Anonymous Poster

making anhydrous from hydrous reagent

12/17/2009 5:26 PM

hello

I am trying to make 100mM of Fe(NH4)2SO4, but all I have is Fe(NH4)2SO4*6H2O. Can anyone please show me how to calculate the amount I need to weight out to make 1 L of 100mM of the anhydrous ferrous amonium sulfate?

thanks
Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
2
GeoffreyBernardo
Member

Join Date: Oct 2008
Posts: 8
Good Answers: 1
#1

Re: making anhydrous from hydrous reagent

12/18/2009 2:32 AM
  1. Obtain the molecular mass of the anhydrous ferrous ammonium sulphate (FAS) in g/mol.
  2. Calculate the mass of the anhydrous FAS (in g) necessary for 1 L of 100 mM solution, by multiplying the molecular mass by 100 x 10^(-3).
  3. Obtain the molecular mass of water in g/mol.
  4. Calculate the mass of water in the hydrous FAS (in g) that contains the requisite mass of anhydrous FAS, by multiplying the molecular mass of water by 6 x 100 x 10^(-3).
  5. Add the mass of anhydrous FAS to the mass of water to obtain the mass of hydrous FAS necessary for 1 L of 100 mM solution of anhydrous FAS.
Reply Good Answer (Score 2)
No more Good Answers. Go to first "Almost" Good Answer
nghi
Participant

Join Date: Dec 2009
Posts: 2
#2
In reply to #1

Re: making anhydrous from hydrous reagent

12/18/2009 9:07 AM

hi.

If I add those mass of anhydrous and H2O for 100mM together then I have the MW which is on the label of the hydrous reagent on the bottle. So I just need to use the MW on the label to make the anhydrous form of this compound? I thought we have to to remove the water in this scenario

thanks
Reply
GeoffreyBernardo
Member

Join Date: Oct 2008
Posts: 8
Good Answers: 1
#3
In reply to #2

Re: making anhydrous from hydrous reagent

12/18/2009 5:35 PM

You might as well just use the molecular mass of the hydrous FAS. It gives the same result. 1 M hydrous FAS contains 1 M anhydrous FAS.
Reply
okiescienceprof
Power-User

Join Date: Oct 2009
Location: Oklahoma
Posts: 137
Good Answers: 5
#4

Re: making anhydrous from hydrous reagent

12/18/2009 11:32 PM

The molecular formula Fe(NH4)2SO4*6H20 is incorrect try Fe(NH4)2(SO4)2*6H20 ferrous ~ Fe+2 ammonium ~ +1 sulfate ~ -2
Reply Score 1 for Good Answer
Go to Next "Almost" Good Answer
okiescienceprof
Power-User

Join Date: Oct 2009
Location: Oklahoma
Posts: 137
Good Answers: 5
#5

Re: making anhydrous from hydrous reagent

12/19/2009 12:14 AM

You will need one tenth of the gram formula mass of the ferrous ammonium sulfate hexahydrate to prepare one liter 100nM (or 0.1M) of that solution...use caution! Be sure to maintain volume (addition H2SO4 is needed for dehydration I believe but checkout carefully) at one liter total.
Reply
babybear
Guru
United Kingdom - Member - Not a new member!

Join Date: Jun 2008
Location: USA/Europe
Posts: 4547
Good Answers: 68
#6

Re: making anhydrous from hydrous reagent

12/19/2009 9:11 PM

Hi Guest,

Can you tell me why you want this please. I will then tell you exactly how to do this................

__________________
 Take it easy, bb. >"HEAR & you FORGET<>SEE & you REMEMBER<>DO & you UNDERSTAND"<=$=|O|=$=>"Common Sense is Genius dressed in its Working Clothes"<>[Ralph Waldo Emerson]
Reply Score 1 for Good Answer
No more "Almost" Good Answers.
nghi
Participant

Join Date: Dec 2009
Posts: 2
#7
In reply to #6

Re: making anhydrous from hydrous reagent

12/21/2009 9:28 AM

hi

What I need is to make 100mM of Fe(NH4)2SO4, but I only have Fe(NH4)2SO4 *6H2O.

thank you
Reply
okiescienceprof
Power-User

Join Date: Oct 2009
Location: Oklahoma
Posts: 137
Good Answers: 5
#8
In reply to #7

Re: making anhydrous from hydrous reagent

12/21/2009 10:56 AM

nghi Are you reading the comments above?...it appears that you are inexperienced in preparing chemical solutions. I respectfully suggest you leave it to someone who will use the appropriate cautions. Since dehydrating Fe(NH4)2(SO4)2*6H2O or hydrated FAS (your formula does not exist) requires addition of concentrated sulfuric acid (which can can create enough heat to cause splattering if not mixed correctly). The solution you are preparing is also dangerous to the skin, liver, and spleen.
Reply
pauls_14
Commentator
United States - Member - New Member

Join Date: May 2009
Location: Minnesota, USA
Posts: 89
Good Answers: 2
#9

Re: making anhydrous from hydrous reagent

12/22/2009 8:19 AM

Is this homework or a take home test?

__________________
 "Obviously you're not a golfer." - The Dude
Reply
Reply to Forum Thread
Have a Different Question?
9 comments

Good Answers:

These comments received enough positive votes to make them "good answers".

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Copy to Clipboard

Users who posted comments:

babybear (1); GeoffreyBernardo (2); nghi (2); okiescienceprof (3); pauls_14 (1)

Previous in Forum: Where Can I find for High Quality (Free) Online Scientific Journals?   Next in Forum: Plastisol Ink

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Chemical & Material Science:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (87 right now)
Show Members
Advertisement