Question

I have 345 mL of a 1.5 M NaCl solution. If I boil the water until the volume of the solution is 250 mL, what will the molarity of the solution be?

Answer 1

The amount of substance, of `NaCl` solute is constant. The answer is approx. `2` `mol*L^-1`.

Explanation:

`"Concentration"` `=` `"Mass"/"Volume of solution"`

Initially I had `0.345*cancelLxx1.5*mol*cancel(L^-1)` `=` `0.518` `mol`.

After I boil off some of the water, I have a new volume of solution but the SAME amount of SOLUTE, i.e. `0.518` `mol`.

Thus `"Concentration"` `=` `(0.518*mol)/(0.250*L)` `=` `??mol*L^-1`