A solution is made up of 15.0 mL of 4.50 x 10^-3 M Fe(NO3)3 15.0 mL of 4.50 x 10

ID: 949679 • Letter: A

Question

A solution is made up of

15.0 mL of 4.50 x 10^-3 M Fe(NO3)3

15.0 mL of 4.50 x 10^-3 M KSCN

10.0 mL of water

It is determined that the following reaction occurs

Fe3+ (aq) + SCN- (aq) = Fe(SCN)2+ (aq)

1. What is the concentration (in M) of Fe3+ in the resulting solution before any reaction takes place? Assume that volumes are addictive.

2. At equilibruim, [Fe(SCN)2+] is 1.20 x 10^-3 M. What is [Fe3+] at equilibrium?

3. What is K for the reaction at the temperature in which the experiment is performed?

1. [Fe3+] initial = 4.50 x 10^-3 M x 15 ml/40 ml = 1.69 x 10^-3 M

2. When, [Fe(SCN)]2+ is 1.2 x 10^-3 M,

[Fe3+] at equlibrium = 1.69 x 10^-3 - 1.20 x 10^-3 = 4.90 x 10^-4 M

3. [SCN-] equilibrium = 4.90 x 10^-4 M

K = (1.20 x 10^-3)/(4.90 x 10^-4)^2 = 4998

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