How can chem equations be balanced with out altering the subcripts?

Question

How can chem equations be balanced with out altering the subcripts?

Answer 1

By adding coefficients. Example:

Balance NaOH + H2SO4 --> Na2SO4 + H2O

You need to add coefficients so the same number of each element is on each side. You end up with:

2NaOH + H2SO4 --> Na2SO4 + H2O

Answer 2

You can't change the subscripts. You can change the coefficients in from of the species.  Example)

unbalanced form: C2H6 + O2 --> CO2 + H2O

Notice that if we change the subscript, we change the compound

Balanced form:  2C2H6 + 7O2 --> 4CO2 + 6H2O