Kinetics of Crystal Violet
Spectrophotometric Analysis of Reaction Rate
Study the kinetics of crystal violet fading reaction using spectrophotometry. Observe the color change over time and analyze the reaction rate through absorbance measurements.
Abs: 1.00
Wavelength: 590 nm
Time (s)
Absorbance
0.5 mM
Observation:
The purple crystal violet solution will fade to colorless as the reaction with hydroxide proceeds. The absorbance decreases exponentially over time.
Reaction Rate:
Initial rate: 0.00 mM/s
The Science Behind Crystal Violet Kinetics
Key Concepts:
Crystal violet fading is a classic kinetics experiment:
- Reaction: CV+ + OH- → CVOH (colorless)
- Pseudo-first order when [OH-] >> [CV+]
- Spectrophotometry measures absorbance at λmax ≈ 590 nm
- Beer-Lambert Law: A = εlc (A = absorbance, ε = molar absorptivity, l = path length, c = concentration)
Kinetic Analysis:
Plotting ln(Absorbance) vs time gives a straight line for first-order reactions. The slope equals -k (rate constant).
Applications:
Used to study reaction mechanisms, determine rate laws, and understand chemical kinetics principles.
