Can you explain balancing chemical equations in detail?

Question

Caleb Adams · Accepted Answer

Representation of chemical reactivity by symbols follows two absolute rules:

#1." Mass is conserved."# #2." Charge is conserved."# What does this mean? Since mass is a fundamental property of atoms and molecules, it follows that atoms and molecules are conserved in EVERY chemical reaction. For example, if we start with 10 g of reactant FROM ALL SOURCES, AT MOST we can get 10 g of product; and in practice we are not even going to get that. Thus, if we look at an equation like this one: #CH_4(g) + O_2(g) rarr CO_2(g) + H_2O(l)# We can dismiss it out of hand because it is unbalanced (why not?), and we know that it is not representative of reality. Conversely, though, for... #underbrace(CH_4(g) + 2O_2(g) rarr CO_2(g) + 2H_2O(l))_"80 g of reactant gives 80 g of product"# Here, charge and mass are balanced, making this a plausible depiction of reality. I know I am being absolute when I say that charge and mass are conserved, but this reflects EVERY CHEMICAL REACTION, EVERY EXPERIMENT EVER PERFORMED: when a reaction is studied in detail, #"garbage out has always equalled garbage in."# And how else can we be certain that stoichiometry works and that masses are conserved if not through experimentation and the in-depth, quantitative analysis of specific chemical reactions? We have a particle view of chemical reactivity today, and our ideas, developed over only about 200–300 years, insist that matter is conserved. The fact that molecules and atoms themselves have discrete masses, which are certainly measurable, supports our notion of conservation of mass. Every chemical reaction ever performed (and as far as we know, TO BE PERFORMED) displays conservation of mass. Charge and mass are conserved, and this concept can be expanded to the representation of redox reactions, where we can use the electron as a charged particle that is transferred between species in a redox process. If this all seems a lot to take in, remember you will only be asked to balance equations to which you have already been introduced. Alkanes combust in air to give carbon dioxide and water, iron combines with oxygen to give rust, #Fe_2O_3# and #FeO#. You have suggested a reasonable chemical pathway if you can write a chemical equation that balances mass and charge. Redox equations can be found here.

Noah Aldrich · Answer

undefined Chemical equations must be balanced by adjusting coefficients to ensure that the number of atoms of each element is the same on both sides of the equation. To begin, write down the equation that is out of balance. Next, use coefficients to balance one element at a time while keeping in mind the law of conservation of mass. Continue this process until all elements are balanced.