# Do the compounds in a chemical equation need a net charge of zero when predicting reaction products?

For predicting reaction products in chemical equations, I am not sure of what the subscripts would look like in the product side. I know the types of reactions, but when you predict the products, do the compounds need a net charge of zero? If the net charge of zero does not matter, would the subscripts in the products look the same in the reactants and just the coefficients are different? Thank you for your help in advance. Here are some examples as well:

EX:

__C2H2 + __O2 -> (<-Reactants)

(Products->) -> __CO2 + __H2O (<-my guess)

EX:

__LiOH + __Fe(NO3)3 ->

                > LiNO3 + FeOH


The products that are shown in the example are my guess, so they may not be correct. I am also not sure how I would balance equations for combustion.

## 2 Answers

Yes, the compounds on the products side do need a net charge of zero. You are correct in the products of the combustion reaction being CO2 and H2O. I balanced it using a trial and error method, but it does take a few trials to get to the answer. I will give you a hint, the coefficient for O2 is 5.

The second equation is a precipitation reaction, assuming it takes place in solution. Since Iron (III) Hydroxide is insoluble then the reaction will occur. In order to determine the subscripts for the products, you need to first determine the charges on the individual ions. Li is a group 1 metal. It will have a charge of +1. OH is a hydroxide ion, it always has a charge of -1. Iron (Fe) typically has a charge of either +2 or +3. In order to determine its charge for the products, you have to determine its charge on the reactant side. Since N03 always has a charge of -1 and there are 3 of them on the reactant side, than Fe has a +3 charge. Because Fe has a +3 charge and the OH has a -1 charge you will need 3 OH ions for every 1 Fe ion = Fe(OH)3. The Li(NO3) is already neutral since Li is +1 and NO3 is -1.

Hope this helps!

Compounds on the product side of a reaction do not necessarily have to have zero charge.

However, the fundamental principles of conservation of mass and conservation of charge mean that you must have the same number of each atom type on both sides of a reaction arrow, and the same net charge. Net charge means, that a reaction is allowed if an overall reactant charge of $1-$ gives a set of products with an overall charge of $1-$, but not if the products’ overall charge is $2-$. An electron is permitted to be on either side of the reaction.