Question

A 15 ml of a 7 % (w/w) stock solution of MgS (Molar mass = 56 g/mol and %3D specific gravity 1.26) was added to 20 ml of water to prepare a less concentrated solution. Calculate the concentration (in mol/l=M) for the prepared solution (Hint find the concentration of the stock solution first).

Answer 1

Step-by-step explanation:

Here, we want to calculate the concentration of the prepared solution

We start by calculating the concentration of the prepared solution. This is the same as the molarity of the prepared solution

Mathematically, we have that as follows:

`\lbrack\text{ }\frac{\text{ \%}* d}{MW}\rbrack*10\text{ = molarity}`

where d is the specific gravity, MW is the molecular weight

Substituting the values, we have it that:

`(7*1.26)/(56)*10\text{ = 1.575 M}`

From what we have above 1.575 M is present in 1 L

The amount present in 15 ML will be: