The rate of the crystal violetNaOH reaction is given by the

The rate of the crystal violet/NaOH reaction is given by the following generalized rate law: Rate = k’[CV+]y

where k’ is the pseudo rate constant defined by

k’ = k [OH-]x , where k is the actual rate constant

The actual rate constant can be calculated using the pseudo rate constant and the [OH-] present in the reaction mixture. If the reaction mixture is prepared by mixing 5.0 mL of 1.00 x 10-4 M crystal violet solution with 5.0 mL of distilled water and 10.0 mL of 0.10 M NaOH, what is the [OH-] in the reaction mixture?

Solution

Crystal violet experiment

Reactions mixture has,

5.0 ml x 1 x 10^-4 M crystal violet + 5.0 ml distilled water + 10 ml x 0.1 M NaOH

Total volume of solution = 5 + 5 + 10 = 20 ml

[OH-] in the reaction mixture = 0.10 M x 10 ml/20 ml

                                              = 0.05 M

[formula,

moles (mol) = molarity (M) x volume (L)]]