How to calculate n factor in non-redox reactions and other such reactions?

I know these facts about n factor:
- n factor of acid = no. of replaceable H+ ions per mole of acid (basicity of acid).

  • n factor of base = no. of replaceable OH- ions per mole of base (acidity of base).

  • n factor of salt = summation (no. of moles of a cation in one mole of salt × oxidation state of it).

  • n factor of a substance in redox reaction = total number of electrons gained or lost per mole = total change in oxidation number per molecule.

Now here comes my doubt. I read n factor of non redox reaction = product of displaced mole × its charge. I am not sure I understood this. Could someone please explain this?

Also, for neutralization reactions in which acid does not have H+ ion and/or base does not have OH- ion, how do you calculate n factor? What about other types of reactions?

For Ex: calculate n factor of Cao in CaCO3 ----> CaO+CO2

Can someone mention any other rules of calculating n factor if any? Thanks.

1 Answer
Mar 31, 2018

You are digging yourself into a hole.

Explanation:

I have not come across the term #"n-factor"#, but it is likely to be another word for #"stoichiometry"#. And what is this? It is the chemical principle that #"garbage OUT equals garbage in"#...and it encapsulates the KNOWN observation that for #10*g# reactant in a chemical reaction, there can be at most #10*g# of product.

So if you see a reaction in which this principle is violated...e.g.

#C_2H_6(g) +O_2(g) rarr 2CO_2(g) + 2H_2O(l)#

You know that it cannot be accepted as a representation of chemical reality. On the other hand for...

#underbrace(C_2H_6(g) + 7/2O_2(g))_"142 g" rarr underbrace(2CO_2(g) + 3H_2O(l))_"142 g"#

Mass is balanced here...and so this reaction obeys the principle of stoichiometry. And this principle has governed ALL chemical reactions that have been studied in any detail. And today we have a particle view of reactivity, and these principles, developed only after a few hundred years are basic to chemical calculation. That atoms and molecules themselves have discrete and measurable masses, supports our notion of stoichiometry.

And a chemical reaction not only conserves mass, it conserves charge as well...and in redox reactions we introduce electrons as conceptual particles that are conceived to have a negative charge. And in an oxidation reaction ... as shown .... charge is CONSERVED as well as mass.

#Fe(s) rarr Fe^(2+) + 2e^-#

The electrons are presumed to go somewhere....i.e. they cause a reduction of another reagent. And for iron the other reagent is typically oxygen gas...

#1/2O_2(g) + 2e^(-) rarr O^(2-)#

And so given a reaction, the two questions you axe yourself are: #"(i) is mass conserved"#; and #"is charge conserved?"#. And if the answer is no you have still got work to do.

The reaction you propose is NON-REDOX....electrons are not to be transferred. But it still (and must!) follows conservation of mass:

#CaCO_3(s) + Delta rarr CaO(s) + CO_2(g)uarr#

Because it is an endothermic reaction, we put the #Delta# symbol in to remind us of the heat input.

Anyway, again your question is open-ended, and I acknowledge that I may not have addressed your concern. If so, please try to clarify your query.