Question

DATE:
Balancing chemical
coot H2O
y (6 H12 O6 + O2 left hand and right hand balancing​

Answer 1

Answer:

As a first remark, you cannot have the same chemical species (here, H2O) among the reactants and among the products as well. So, you have to cancel it, either from the reactants or the products. If you remove it from reactants, only CO2 would be left as reactant, while the products include hydrogen-containing species glucose (C6H12O6). Since one basic law of chemistry is the impossibility of element transmutation (lead cannot be converted into gold!), some hydrogen containing species (namely, H2O) has to be present among the reactants; therefore, H2O has to be excluded from the products.

So, a more correct, still unbalanced, equation is : CO2 + H2O = C6H12O6 + O2 .

A practical, not scientific, way to balance relies on the fact that chemical reactions request the conservation of atoms, element by element. Remark that all the carbon atoms in the products are in the glucose (six carbon atom per glucose molecule), while all the carbon atoms in the reactants are in carbon dioxide (one atom per molecule). So, tentatively, to balance the number of carbon atoms between reactants and products, write 6 as stoichiometric coefficient of CO2, and, implicitly, 1 as stoichiometric coefficient of C6H12O6. You get, as partial result,

6 CO2 + ? H2O = 1 C6H12O6 + ? O2 .

Now remark that all the hydrogen atoms in the products are in glucose (twelve H atoms per molecule), while in the reactants all of them are in water (two H atoms per molecule). So you need 6 water molecule to supply all the hydrogen atoms needed for one glucose molecule. Therefore, write a stochiometric coefficient 6 for water, and you get

6 CO2 + 6 H2O = 1 C6H12O6 + ? O2 .

At this point, remark that you have 18 oxygen atoms in the reactant molecules as a whole, while, among the products, the glucose molecule contains only 6 such atoms. Evidently, by the conservation of atoms of each element, the other 12 oxygen atoms have to be assigned to the oxygen molecule; since it is diatomic, six O2 molecules will be needed to balance the equation. The final result is

6 CO2 + 6 H2O = C6H12O6 + 6 O2 ,

where I dropped stoichiometric coefficient 1 of glucose, because, when it is just 1, it is customary not to write it explicitly, leaving it as understood.

Much longer to write than to do.

Explanation: