Question

Which of the following solutions would have [Fe3+] = 0.020 M?

A. 0.40L of 0.050 M Fe(NO3)3
B. 0.80 L of 0.020 M Fe2(SO4)3
C. 0.50 L of 0.040 M FeC6H4O
D. 0.50 L of 0.010 M Fe(C204)3

Answer 1

None of the given options

Step-by-step explanation:

Let's go case by case:

A. No matter the volume, the concentration of Fe(NO₃)₃ (and thus of [Fe³⁺] as well) is 0.050 M.

B. We can calculate the moles of Fe₂(SO₄)₃:

• 0.020 M * 0.80 L = 0.016 mol Fe₂(SO₄)₃

Given that there are two Fe⁺³ moles per Fe₂(SO₄)₃ mol, in the solution we have 0.032 moles of Fe⁺³. With that information in mind we can calculate [Fe⁺³]:

• 0.032 mol Fe⁺³ / 0.80 L = 0.040 M

C. Analog to case A., the molar concentration of Fe⁺³ is 0.040 M.

D. Similar to cases A and C., [Fe⁺³] = 0.010 M.

Thus none of the given options would have [Fe⁺³] = 0.020 M.