Balancing Chemical Equations
Date: 02/04/2004 at 20:07:03 From: Aaron Subject: Balancing chemical equations I am having trouble balancing very complex chemical equations, like this one: HIO3 + FeI2 + HCl -> FeCl3 + ICl + H2O. After I balance all the elements other than hydrogen and oxygen I cannot balance the hydrogen and oxygen.
Date: 02/04/2004 at 21:52:50 From: Doctor Rob Subject: Re: Balancing chemical equations Thanks for writing to Ask Dr. Math, Aaron! To balance any chemical equation, put unknowns for the number of molecules of each compound on both sides: a*HIO3 + b*FeI2 + c*HCl -> d*FeCl3 + e*ICl + f*H2O. Then for each element appearing, set the number of atoms on the left equal to the number of atoms on the right: H: a + c = 2*f. I: a + 2*b = e. O: 3*a = f. Fe: b = d. Cl: c = 3*d + e. Now solve this system of equations for b, c, d, e, and f in terms of a by using substitutions and combinations of the above: b = (4/5)*a, c = 5*a, d = (4/5)*a, e = (13/5)*a, f = 3*a. Now put a equal to the greatest common denominator of the coefficients appearing, (a = 5) and evaluate b, c, d, e, and f: a = 5, b = 4, c = 25, d = 4, e = 13, f = 15. That means that the equation will be balanced if you have 5 HIO3 + 4 FeI2 + 25 HCl -> 4 FeCl3 + 13 ICl + 15 H2O. Feel free to write again if I can help further. - Doctor Rob, The Math Forum http://mathforum.org/dr.math/
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