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Topic: How to make this equation correct.  (Read 4207 times)

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convict11

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How to make this equation correct.
« on: June 09, 2006, 12:43:02 AM »
3Na2CO3  + FeCl3  ----------> NaCl + Fe2(CO3)3


Ca(OH)2 + Al2(SO4)3 ---------> Ca(SO4)3 + Al2(OH)2

The second half of both of these equations are correct. I am not really sure how to make them correct and need help on forming chemical equations. Can anyone help?

Offline AWK

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Re: How to make this equation correct.
« Reply #1 on: June 09, 2006, 01:42:03 AM »
3Na2CO3  + FeCl3  ----------> NaCl + Fe2(CO3)3


Ca(OH)2 + Al2(SO4)3 ---------> Ca(SO4)3 + Al2(OH)2

The second half of both of these equations are correct. I am not really sure how to make them correct and need help on forming chemical equations. Can anyone help?
These are examples of double exchange reactions. Count charges of cations and anions!
eg:
CaCl2 + Na3PO4 = Ca3(PO4)2 + NaCl
Ca = 2+
Cl = 1-
Na - 1+
PO4 - 3-
Start counting from the highest charges on the left side
3 x 2+ + 2 x 3- = 0 hence you need 3 CaCl2 and 2 Na3PO4
The rest is straighforward 6 Cl- need 6 Na+
and reaction is:
3CaCl2 + 2Na3PO4 = Ca3(PO4)2 + 6NaCl
AWK

Offline Donaldson Tan

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Re: How to make this equation correct.
« Reply #2 on: June 09, 2006, 12:19:45 PM »
3Na2CO3  + FeCl3  ----------> NaCl + Fe2(CO3)3
This reaction is not possible, because Fe3+ has a high polarising power due to its high charge. Instead, the carbonate ion breaks due to the polarising nature of Fe3+ and you get Fe2O3 and CO2


Quote from: convict11 link=topic=9164.msg43176#msg43176
Ca(OH)2 + Al2(SO4)3 ---------> Ca(SO4)3 + Al2(OH)2
The valency of Al is 3, there is no way you can get Al2(OH)2. The valence for Ca is 2, so there is no way you can get Ca(SO4)3. Try balancing this equation instead: Ca(OH)2 + Al2(SO4)3 ----> CaSO4 + Al(OH)3

On the side note, the structure of Al(OH)3 is quite debatable. This is due to high acidic character of the Al3+ ion. One school of thought supports the original Al(OH)3 structure while others view Al(OH)3 as the hydrated form of Al2O3, ie. 2Al(OH)3 = Al2O3.3H2O
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

Offline AWK

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Re: How to make this equation correct.
« Reply #3 on: June 12, 2006, 05:39:15 AM »
Quote
On the side note, the structure of Al(OH)3 is quite debatable. This is due to high acidic character of the Al3+ ion. One school of thought supports the original Al(OH)3 structure while others view Al(OH)3 as the hydrated form of Al2O3, ie. 2Al(OH)3 = Al2O3.3H2O
This statement is not true.
Al(OH)3 exists in at least four crystal forms as minerals: Bayerite, Norstrandite, Doyleite and Gibbsite.
AWK

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