Why are #"molality"#, and #"mass percent"# SOMETIMES used in preference to #"molarity"#?

1 Answer
May 22, 2017

Answer:

Because both #"amount of substance"# and #"mass"# are independent of temperature..........

Explanation:

#"Molality"="Moles of solute"/"Kilograms of solvent"#; both numerator and denominator do not vary with temperature.

#"Mole fraction"="Moles of one component"/"Total number of moles"#.

#"Mass %"="Mass of component element"/"Molar mass"xx100%#

And by the same token, consider the alternative, #"molarity"="moles of solute"/"volume of solution"#...

Now the numerator is invariant with temperature, but the denominator DOES vary with temperature. Of course, at so-called infinite dilution, #"molarity"#, and #"molality"# are essentially equivalent.