Pre-lab 5: Determination of an Equilibrium Constant

Express the equilibrium constant for today’s reaction:

Fe3+(aq) + SCN- (aq) ← → FeSCN2+(aq)

Keq = [FeSCN2+] / [Fe3+] [SCN-]

FeSCN2+ is light sensitive? How are you going to handle this problem?

Yes, don’t wait longer than 5 minutes before taking it out

An equilibrium constant with a low magnitude indicates that:

Reaction favors stating materials

The reaction of Fe3+ with SCN- ions in aqueous solution will be confirmed by:

Solution will turn to reddish color

The limiting agent when excess of Fe3+ ions are used (part A of today’s experiment) is:

SCN- ions

The greater the concentration of FeSCN2+ (circle all that applies),

The smaller is the relative amount of light that passes through the cuvette, the greater is the absorption value

If you take 5.0mL of 0.2M Fe(NO₃)₃, 4.0mL of 0.002M KSCN, and 41.0mL of water, what is the molar concentration (before the reaction takes place ) of Fe(NO₃)₃?

0.02