What is formality?
Here's how you can think about formality.
Simply put, formality is a way of expressing the concentration of a compound in solution.
More specifically, formality is defined as moles of solute per liters of solution.
This should sound very familiar - isn't molarity defined as moles of solute per liters of solution?
So is fomality the same as molarity? Sometimes.
Formality does not take into account what happens to a chemical compound once it's dissolved. That is, it won't matter if the compound is an electrolyte or a a non-electrolyte.
If you dissolve sodium chloride,
#"NaCl"_text((aq]) -> "Na"_text((aq])^(+) + "Cl"_text((aq])^(-)#
So if you dissolve one mole of
#F = "moles of solute"/"liters of solution"#
#F = "1 mole NaCl"/"1 L" = "1 formal"#
The molarity of this solution, on the other hand, is said to be
And here's the difference between formality and molarity.
Molarity actually takes into account what happens to the solute once it's dissolved. Formality does not.
Check out these examples for a more detailed explanation