Question

A solution is made by adding 29.1 mL of concentrated perchloric acid ( 70.5 wt% , density 1.67 g/mL ) to some water in a volumetric flask, and then adding water to the mark to make exactly 250 mL of solution. Calculate the concentration of this solution in molarity.

Answer 1

The concentration of the solution is 1.364 molar.

Step-by-step explanation:

Volume of perchloric acid = 29.1 mL

Mass of the solution = m

Density of the solution = 1.67 g/mL

`m=1.67 g/mL* 29.1 mL=48.597 g`

Percentage of perchloric acid in 48.597 solution :70.5 %

Mass of perchloric acid in 48.597 solution :

=
`(70.5)/(100)* 48.597 = 34.261 g`

Moles of perchloric acid =
`(34.261 g)/(100.46 g/mol)=0.3410 mol`

In 29.1 mL of solution water is added and volume was changed to 250 mL.

So, volume of the final solution = 250 mL = 0.250 L (1 mL = 0.001 L)

`Molarity=(Moles)/(Volume (L))`

`=(0.3410 mol)/(0.250 L)=1.364 M`

The concentration of the solution is 1.364 molar.