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

Answer:

Solvent evaporated = 172.5 mL

Explanation:

Considering:

$Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}$

Or,

$Moles =Molarity \times {Volume\ of\ the\ solution}$

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

$Moles=0.275 \times {230\times 10^{-3}}\ moles$

Moles in the solution  = 0.06325 moles

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

Left solvent = 230 - x mL = $\frac{230-x}{1000}\ L$

Moles = 0.06325 moles  

Molarity = 1.10 M

So, applying in the expression for molarity as:-

$1.10=\frac{0.06325}{230 - x}\times 1000$

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

$x=\frac{345}{2}$

$x=172.5$

Solvent evaporated = 172.5 mL