Answer to Question #86041 in General Chemistry for thomas

Question

In the laboratory you dissolve 12.6 g of iron(II) nitrate in a volumetric flask and add water to a total volume of 500 mL.

1. What is the molarity of the solution? ______ M.
2. What is the concentration of the iron(II) cation? ______M.
3. What is the concentration of the nitrate anion? _______ M.

Answer 1

Fe(NO₃)₂ -> Fe²⁺ + 2NO₃^-

n=m/M

n(Fe(NO₃)₂) = 12.6 g/179.87 g/mol = 0.07 mol

1. c(Fe(NO₃)₂) = 0.07 mol/0.5 L = 0.14 mol/L = 0.14 M
2. According to equation n(Fe²⁺) = n(Fe(NO₃)₂)= 0.07 mol

c(Fe²⁺) = 0.07 mol/0.5 L = 0.14 mol/L = 0.14 M

3.According to equation mole ratio n(Fe(NO₃)₂):n(NO₃^-) = 1:2, then n(NO₃^-) = 2*n(Fe(NO₃)₂) = 2*0.07 mol = 0.14 mol

c(NO₃^-) = 0.14 mol/0.5L = 0.28 mol/L = 0.28M