Question

If 2.63 g Fe(NO3), is dissolved in enough water to make exactly 460 mL of solution, what is the molar concentration of nitrate ion? M of Fe(NO3)3=241.86 g/mole

Answer 1

mass(Fe(NO3)3)= 2.63 g

use:
number of mol of Fe(NO3)3,
n = mass of Fe(NO3)3/molar mass of Fe(NO3)3
=(2.63 g)/(2.419*10^2 g/mol)
= 1.087*10^-2 mol
volume , V = 4.6*10^2 mL
= 0.46 L


use:
Molarity,
M = number of mol / volume in L
= 1.087*10^-2/0.46
= 2.364*10^-2 M

1 Fe(NO3)3 has 3 NO3-

So,
[NO3-] = 3*[Fe(NO3)3]
= 3*2.364*10^-2 M
= 0.0709 M
Answer: 0.0709 M