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A student prepared this solution by mixing the following solutions: 4.00 mL of 0

ID: 947892 • Letter: A

Question

A student prepared this solution by mixing the following solutions:

     4.00 mL of 0.00250 M Fe(NO3)3
     3.00 mL of 0.00250 M KSCN
     3.00 mL of 0.050 M HNO3

From a plot of absorbance versus concentration of [Fe(SCN)]2+, the equilibrium concentration of [Fe(SCN)]2+ was determined to be 2.8 x 10-4 M. Calculate the initial concentration of Fe3+ before the system is allowed to proceed to equilibrium.

Question 4 options:

1.20 x 10^-3 M

1.00 x 10^-3

4.32 x 10^-4

0.0480 x 10^-3 M

0.0460 X 10^-3 M

1.20 x 10^-3 M

1.00 x 10^-3

4.32 x 10^-4

0.0480 x 10^-3 M

0.0460 X 10^-3 M

Explanation / Answer

Using law of equivalence;

M1V1=M2V2

0.0025 M Fe(NO3)3 * 2 mL = M2 * 10mL

M2 = (0.0025 M * 2 mL) / 10 mL

M2 = 0.0005 M Fe3+