Answer :
The given question is incomplete. the complete question is : If 5.15 g[tex]Fe(NO_3)_3[/tex] is dissolved in enough water to make exactly 323 ml of solution, what is the molar concentartion of nitrate ion.
Answer: The molar concentartion of nitrate ion is 0.195.
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.
Given : 5.15 g of [tex]Fe(NO_3)_3[/tex] is dissolved
Volume of solution = 323 ml
[tex]Molarity=\frac{n\times 1000}{V_s}[/tex]
where,
n= moles of solute
[tex]Moles=\frac{\text{Given mass}}{\text{Molar mass}}=\frac{5.15g}{242g/mol}=0.021moles[/tex]
[tex]V_s[/tex] = volume of solution = 323 ml
[tex]Molarity=\frac{0.021\times 1000}{323}=0.065M[/tex]
As 1 M of [tex]Fe(NO_3)_3[/tex] gives 3 M of [tex]NO_3^-[/tex] ions.
Thus 0.065 M of [tex]Fe(NO_3)_3[/tex] gives = [tex]\frac{3}{1}\times 0.065=0.195M[/tex] of [tex]NO_3^-[/tex] ions.
The molar concentartion of nitrate ion is 0.195.