Answer to Question #85960 in General Chemistry for thomas

Question

If 4.96 g Fe(NO3)3 is dissolved in enough water to make exactly 478 mL of solution, what is the molar concentration of nitrate ion?

A. 4.29×10-2 M
B. 1.43×10-2 M
C. 0.129 M
D. 306 M
E. 1.29×10-4 M

Answer 1

Fe(NO₃)₃->Fe³⁺+3NO₃^-

n(Fe(NO₃)₃)=4.96g/241.88g/mol=0.0205 mol

According to equation 1 mole if Fe(NO₃)₃ gives 3moles of NO₃^-, then n(NO₃^-)=3*n(Fe(NO₃)₃)= 0.0205*3=0.0615 mol

c(NO₃^-)= 0.0615mol/0.478L= 0.129 mol/L=0.129M

Answer:C.0.129M