Question

4. A 230.-mL sample of a 0.275 M solution is left on a hot plate overnight; the following morning the solution is 1.10 M. What volume of solvent has evaporated from the 0.275 M solution?

Answer 1

Solvent evaporated = 172.5 mL

Step-by-step explanation:

Considering:

`Molarity=(Moles\ of\ solute)/(Volume\ of\ the\ solution)`

Or,

`Moles =Molarity * {Volume\ of\ the\ solution}`

Given :

For initial concentration solution :

Molarity = 0.275 M

Volume = 230 mL

The conversion of mL to L is shown below:

1 mL = 10⁻³ L

Thus, volume = 230×10⁻³ L

`Moles=0.275 * {230* 10^(-3)}\ moles`

Moles in the solution = 0.06325 moles

The solvent will evaporated. Let the evaporated solvent be x mL

Left solvent = 230 - x mL =
`(230-x)/(1000)\ L`

Moles = 0.06325 moles

Molarity = 1.10 M

So, applying in the expression for molarity as:-

`1.10=(0.06325)/(230 - x)* 1000`

`1.1\left(230-x\right)=63.25`

`x=(345)/(2)`

`x=172.5`

Solvent evaporated = 172.5 mL