Question

The molality of pure water is
(a) 55.5
(b) 50.5
(c) 18
(d) 60.5

Answer 1

Water is concentrated stuff, it is (i) dense, and (ii) this density is combined with an exceptionally small molar mass.....

And we wants the quotient...

moles of solute

kilograms of solvent

...and here the solute and the solvent are the same thing...

And so we calculate...

1000

⋅

g

18.01

⋅

g

⋅

m

o

l

−

1

1

⋅

k

g

=

55.5

⋅

m

o

l

⋅

k

g

−

1

...