And for an older treatment of the principles involved, see [this old answer.](https://socratic.org/questions/can-you-explain-balancing-chemical-equations-in-detail) And the fundamental principle of stoichiometry is "garbage in equals garbage out"garbage in equals garbage out. Every chemical reaction must be balanced with respect to mass and charge. A 10*g10⋅g mass of reactants from all sources yields at most a 10*g10⋅g mass of products.
"Molarity"Molarity is a concentration term, i.e. "molarity"="moles of solute"/"volume of solution"molarity=moles of solutevolume of solution...and as such it has the units of mol*L^-1mol⋅L−1.. And so if we have TWO of the three quantities, say "molarity"molarity and "volume"volume, we can get the third.."moles of solute"moles of solute...
…"molarity"xx"volume"="moles"molarity×volume=moles....and this is certainly consistent dimensionally. What do I mean by this?
And a practical example? Well suppose I gots a 100*mL100⋅mL volume of HCl(aq)HCl(aq), that is 1*mol*L^-11⋅mol⋅L−1 with respect to HClHCl. What mass of sodium hydroxide is required for equivalence?
We write out the stoichiometric equation as a preliminary:
HCl(aq) + NaOH(aq)rarr NaCl(aq) +H_2O(l)HCl(aq)+NaOH(aq)→NaCl(aq)+H2O(l)
n_"HCl"=0.100*Lxx1*mol*L^-1=0.100*molnHCl=0.100⋅L×1⋅mol⋅L−1=0.100⋅mol
And for equivalence we require equimolar sodium hydroxide...
0.100*molxxunderbrace(40.0*g*mol^-1)_"molar mass of NaOH"=4.00*g...i.e. a 4*g mass of hydroxide is required for equivalence.
