Question

A 230.-mL sample of a 0.240 M solution is left on a hot plate overnight; the following morning, the solution is 1.75 M. What volume of water evaporated from the 0.24 M solution?

Answer 1

The volume of water evaporated is 199mL

Step-by-step explanation:

Concentration is calculated with the following formula

`C=(n)/(V)`

where n is the number of moles of solute and V is the volume of the solution (in this case is the same as the solvent volume) in liters.

So we isolate the variable n to know the amount of moles, using the volume given in liters

`230mL=0.23L`

`n=C*V=0.240 M*0.23L=0.055 mol`

Now, we isolate the variable V to know the new volume with the new concentration given.

`V=(n)/(C) =0.055mol/1.75M=0.031L=31mL`

Finally, the volume of water evaporated is the difference between initial and final volume.

`V_(ev)= V_(i) -V_(f) =230mL-31mL=199mL`