[Borek]

I need an example of such situation - unfortunately whenever I try I am just balancing, can't locate a loop. I am just too good

[woelen]

?? 

[Borek]

When somebody not fluent in equation balancing starts to work on some 'complicated' case it sometimes end in a circle - "to balance A atoms I have to modify B coefficient, in turn there is not enough C atoms and I have to modify D coefficient - which makes my equation lacking A atoms which forces me to modify B coefficient" - and circle closes here.

I just have troubles constructing such example.

[Albert]

Oh, I think I've got it! You want us to propose you such examples, don't you?

[Borek]

Yes. I have approached several equations trying to make this mistake but I am too efficient in NOT making it

[woelen]

Try this one. When working with the adjustment method, as you mentioned above, this one is hard:

CH3ONa + NaClO2 + HCl --> COCl2 + NaCl + H2O

Balancing by means of linear algebra methods is easy, but balancing by hand may be quite hard for a beginner.

[Borek]

Good one, thanks!

[Borek]

I think I have found a better one - looks much simpler ot first sight:

P₄O₆ -> P₄ + P₂O₄

but is surprisingly hard to balance by inspection.

[Alberto_Kravina]

I balanced it (I don't post the reaction, I don't want to spoil it ... the other members should try to balance it as well...)

[KD00LS]

I find it very easy to attempt to balance the molecules with the most amount of elements, then work down to the molecules with the least amount. That way, when you get down to balancing the last molecule, you won't disrupt any other pre-determined coefficients.

I also balanced this, took me under 30 seconds.

[Borek]

This one will probably take you longer:

P₂I₄ + P₄ + H₂O -> PH₄I + H₃PO₄

[pantone159]

Not so hard.  I is only on the right in 1 place, so is O, then after that H is only on the right in one unknown place, then you just have to count the P's.
Kind of ugly coeffients though.

[KD00LS]

I tried for about 10 minutes, I can't figure that last one out. I can't get the ratio of H to O on the product side to be 2:1 like it is on the reactant side.

[Mitch]

Check Jched, they love comparing methods for these types of things.

[Borek]

Many of these, although some not directly on the subject:

J.Chem.Educ. 22, 266, 461 (1945). 72, 716, 1125 (1995).
J.Chem.Educ. 36, 215 (1959). 74, 1359 (1997).
J.Chem.Educ. 38, 327 (1961). 65, 45 (1988). 74, 1270 (1997). 76, 362 (1999).
J.Chem.Educ. 69, 276 (1992)
J.Chem.Educ. 23, 550 (1946). 36, 77 (1959). 74, 69 (1987). 76, 362 (1999)
J.Chem.Educ. 38, 329 (1961). 74, 1365, 1365 (1997)
J.Chem.Educ. 62, 507 (1985). 72, 894 (1995).
J.Chem.Educ. 73, 507 (1996). 74, 1367, 1368 (1997).
J.Chem.Educ. 54, 704 (1977). 59, 728 (1982). 69, 279 (1992). 71, 295 (1994). 74, 1369 (1997).