Final answer:
The colorimeter should be set to the specific wavelength that corresponds to the maximum absorbance of the substance under investigation in a chemical equilibria experiment, such as 630 nm for a substance that appears blue.
Step-by-step explanation:
The colorimeter should be set to the wavelength that corresponds to the maximum absorbance for the substance being tested in a chemical equilibria experiment. For example, as mentioned in the discussion, if we are observing a substance that appears blue due to its absorption at 630 nm in the orange range of the visible spectrum, the colorimeter should be set to 630 nm for maximum accuracy. The Beer - Lambert Law relates the absorbance of a chromophore at a given wavelength to its concentration, indicating that a higher concentration results in greater absorbance. It's essential to select a wavelength where the absorbance is linear with concentration for precise measurements.
In a titration context, different indicators such as methyl orange, litmus, and phenolphthalein exhibit color changes at different pH levels, affecting the wavelength of light they absorb. Thin-film interference, another phenomenon related to color and light wavelength, can be observed by designing an experiment to see how thin films reflect or transmit specific wavelengths of light.