Question

Which equation shows the proper setup to find the volume of a 0.250 M CaCl2 solution that contains 39.5 g of CaCl2?

Answer 1

Answer: 1.42 L

Explanation: Molarity : It is defined as the number of moles of solute present in one liter of solution.

$Molarity=\frac{\text{given mass of compound}}{\text{molar mass of compound}\times \text{volume of solution is L}}$

Given mass of $CaCl_2$ = 39.5 g

Molar mass of $CaCl_2$ = 111 g/mol

$0.250M=\frac{39.5g}{111}\times \text{volume of solution is L}}$

Volume of solution in L=1.42L

Answer 2

Molarity = number of mole of substance(n) / volume of solution (V).

n(CaCl2) = mass (CaCl2)/M(CaCl2)

M(CaCl2) = 40+2*35.5 = 111 g/mol 

n(CaCl2) =39.5 g CaCl2*1 mol/111g

0.250 M = 39.5 g CaCl2*1 mol/111g*volume of solution (V).

volume of solution (V) = 39.5 g CaCl2*1 mol/(0.250 M*111g) = 1.42 L