How can I calculate molality of pure water?
1 Answer
Sorry, but there actually is an answer. Just like there's a real molar concentration for water by itself (
Let's say you had
At that amount of water, the number of moles is
#"997.0749 g" / ("18.0148 g/mol") = "55.348 mols"#
molality:
#"mol water"/"kg water"# =#"55.348 mols"/"0.9970749 kg" = "55.50991407" ~~ color(blue)("55.510 m")#
molarity:
#"mol water"/"L water" = "55.348 mols"/"1 L" ~~ color(blue)("55.348 M")#
EDIT:
The reason I give these 'absurd' concentrations is that what your teachers don't tell you (and this sounds like spam but it isn't!) is that since the concentration of water is so high as pure water, it isn't often discussed...
...until you need the "molar density"
The molar volume is often used in thermodynamics and liquid-liquid solution contexts, such as when calculating the freezing point depression using the full van't Hoff equation for