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Author Topic: Barium oxalate - help appreciated please  (Read 14385 times)

Offline tazzems

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Barium oxalate - help appreciated please
« on: 23/10/2007 16:07:53 »
Hi all

I have been given this formula: Ba(HC2O4)2 for Barium Oxalate, which i need to prepare and crystalize into salt form.

I have established that i need to use oxalic acid for the process for which i have found many variations as to what the formula is, the text book says (COOH)2 but i cannot seem to balance the equation when using Barium and oxalic acid, and i cannot find anywhere that says how to prepare it.

I am thinking to mix into heating bowl and heat gently to evapourate and then leave to crystalize, is this safe to do?


The equation i got (which isn't balanced at all!!) is:

Ba + (COOH)2 ----------> Ba(HC2O4)2

I HAVE to use the Ba(HC2O4)2 as this was the one thing i was given by my tutor.

Can anyone help me please?
 ???


 

Offline Bored chemist

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Barium oxalate - help appreciated please
« Reply #1 on: 23/10/2007 19:29:29 »
That's a weird barium oxalate. In principle the oxalic acid H2C2O4 can use just one of it's protons and give the (HC2O4)- ion. It's called bioxalate and it's a bit less commonly refered to than the ordinary oxalate ion (C2O4)--.
From barium hydroxide you could make it like this
Ba(OH)2 +  2  H2C2O4  --> Ba(HC2O4)2 + 2 H2O
 

Offline tazzems

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Barium oxalate - help appreciated please
« Reply #2 on: 23/10/2007 19:46:37 »
thanks, thats a great help.

would that be the salt form of barium oxalate then?
in word equation: barium hydroxide + oxalic acid ----> barium oxalate

is barium hydroxide readily available in the lab or would i need to make that before going onto the oxalate?

so hun for all the questions,


 

Offline eric l

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Barium oxalate - help appreciated please
« Reply #3 on: 24/10/2007 08:45:37 »
Bariumhydroxide is probably readily available, and most probably as monohydrate (the most stable form).  (You must take that into account for calculating the amounts of each reagent.)
 

Offline DrDick

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Barium oxalate - help appreciated please
« Reply #4 on: 24/10/2007 17:53:48 »
Ba(HC2O4)2 is no more barium oxalate than NaHCO3 is sodium carbonate (NaHCO3 is actually sodium hydrogen carbonate or sodium bicarbonate).  The more correct name for the former would be barium hydrogen oxalate or, more informally, barium bioxalate (as stated earlier.

Barium oxalate would be BaC2O4.

Having said that, you might be able to make the barium bioxalate from Ba and H2C2O4 (I think you'd might make the barium oxalate instead).

Ba + 2 H2C2O4 --> Ba(HC2O4)2 + H2

Note that in order to oxidize the Ba --> Ba+2, you have to reduce something else (in this case, H+ --> H2).

Dick

 

Offline lightarrow

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Barium oxalate - help appreciated please
« Reply #5 on: 24/10/2007 18:16:51 »
Hi all

I have been given this formula: Ba(HC2O4)2 for Barium Oxalate, which i need to prepare and crystalize into salt form.

I have established that i need to use oxalic acid for the process for which i have found many variations as to what the formula is, the text book says (COOH)2 but i cannot seem to balance the equation when using Barium and oxalic acid, and i cannot find anywhere that says how to prepare it.

I am thinking to mix into heating bowl and heat gently to evapourate and then leave to crystalize, is this safe to do?


The equation i got (which isn't balanced at all!!) is:

Ba + (COOH)2 ----------> Ba(HC2O4)2

I HAVE to use the Ba(HC2O4)2 as this was the one thing i was given by my tutor.

Can anyone help me please?
 ???

When you add Ba2+ to C2O42-, Ba(C2O4) precipitates.  If you want to make Ba(HC2O4)2 from Ba(C2O4) you have to decrease the solution's pH properly, knowing that for oxalic acid
Ka1 ≈ 5*10-2 and Ka2 ≈ 5*10-5.
You have to write the equilibrium:
H2C2O4 reversible arrow H+ + HC2O4-
and make some computations. (don't ask me now, I'm tired  :))
 

Offline tazzems

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Barium oxalate - help appreciated please
« Reply #6 on: 28/10/2007 12:20:42 »
ok none of these seem to be balancing to me! eg:

Ba(OH)2 + 2H2C2O4 = Ba(HC2O4)2 + 2H2O

BA= 1             > Ba = 1
C= 2              > C=2
H=6               > H=6
BUT
O=6               > O=9??



AND:

Ba + 2H2C2O4   =  Ba(HC2O4)2 +H2   (which is the equation i would expect to make)

Ba=1           >  Ba=1
H=4            > H=4
C=2            > C=2
BUT
O=4            >O=8???


Am i wrong?

 :-\
 

Offline tazzems

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Barium oxalate - help appreciated please
« Reply #7 on: 28/10/2007 12:28:02 »
so would this work?

Ba + (H2C2O4)2   =  Ba (HC2O4)2 + H2

 [?]
 

Offline lightarrow

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Barium oxalate - help appreciated please
« Reply #8 on: 28/10/2007 18:19:39 »
ok none of these seem to be balancing to me! eg:

Ba(OH)2 + 2H2C2O4 = Ba(HC2O4)2 + 2H2O

BA= 1             > Ba = 1
C= 2              > C=2
H=6               > H=6
BUT
O=6               > O=9??

AND:

Ba + 2H2C2O4   =  Ba(HC2O4)2 +H2   (which is the equation i would expect to make)

Ba=1           >  Ba=1
H=4            > H=4
C=2            > C=2
BUT
O=4            >O=8???

Am i wrong?

Yes.
I've colored in red your mistakes. I think you are able to correct them from yourself.
« Last Edit: 28/10/2007 18:21:18 by lightarrow »
 

Offline lightarrow

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Barium oxalate - help appreciated please
« Reply #9 on: 28/10/2007 18:23:22 »
so would this work?

Ba + (H2C2O4)2   =  Ba (HC2O4)2 + H2

 [?]
No, the reactions you have written in your previous post are both correct. (H2C2O4)2 is not oxalic acid.
 

Offline Bored chemist

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Barium oxalate - help appreciated please
« Reply #10 on: 28/10/2007 21:46:29 »
When I wrote "Ba(OH)2 +  2  H2C2O4  --> Ba(HC2O4)2 + 2 H2O" I put the extra spaces in for a reason.
1 mole of Ba(OH)2 +  2  moles of H2C2O4  --> 1 mole of Ba(HC2O4)2 + 2 moles of H2O
I guess I should learn how to subscript numbers.
 
 

Offline JimBob

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Barium oxalate - help appreciated please
« Reply #11 on: 29/10/2007 02:30:54 »
Click center "Preview" button, Wait for the screen to come up with all of the things you can do. Highlight the number or symbol to be either superscriped or subscripted (no not magazines!) and click the appropriate button. sup for superscript and sub for subscript.

Check out the preview - it is essential for physics or chemistry - everything (almost) is there.
 

Offline Bored chemist

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Barium oxalate - help appreciated please
« Reply #12 on: 29/10/2007 19:51:09 »
OK, lets see if I can get that to work
When I wrote "Ba(OH)2 +  2  H2C2O4  --> Ba(HC2O4)2 + 2 H2O" I put the extra spaces in for a reason.
 

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Barium oxalate - help appreciated please
« Reply #12 on: 29/10/2007 19:51:09 »

 

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