Which of the following steps correctly describes the preparation of 0.5 m solution of fecl3?
find the molar mass of fecl3 and multiply by 0.5 to find the amount. add this amount in a volumetric flask and add water till the 1 l mark.
find the molar mass of fecl3 and add that amount of fecl3 to a volumetric flask and then add 1 l of water.
find the molar mass of fecl3 and add that amount of fecl3 to a volumetric flask and then add water to the 1 l mark.
find the molar mass of fecl3 and multiply by 0.5 to find the amount. add this amount in a volumetric flask and add 1 l of water.

Option A is correct

Explanation:

Data given:

Steps for preparation of 0.5 M solution = ?

Solution:

Molarity: This the term used for the concentration of the solution. It is the amount of solute in moles dissolve in 1 Liter of solution.

Formula used for Molarity

         Molarity = number of moles of solute / 1 L of solution

From the above definition and formula it is clear that we have to know the following things.

Now:

As we couldn't weight mole on balance so have to convert moles to grams by using molar mass or mass in grams formula

As

   1 mole = mass in grams / molar mass

so to convert mole to mass rearrange the above equation

  mass in grams = 1 mole x molar mass

So,

1 mole of any substance equal to its molar mass

Now, to prepare 0.5 M solution of FeCl₃

So,

1 mole of FeCl₃ = molar mass of FeCl₃

Multiply the molar mass with 0.5

As we know that molarity is the amount of solution in liter of solution not solvent, so we add the calculated amount of solute in volumetric flask and then add water till the 1 L mark. that is amount of solute plus solvent combined form 1 L of Solution.

So, Option A is correct: Find the molar mass of FeCl3 and multiply by 0.5 to find the amount. Add this amount in a volumetric flask and add water till the 1 L mark