Light Absorbance Visible Light Is a Small

Light Absorbance

Visible light is a small portion of electromagnetic radiation that travels between two end points called a wavelength. The shorter the wavelength is the higher the frequency and associated energy. Spectrophotometry measures the amount of light in a wavelength absorbed by the concentration of the solution. The color of the solution is related to the wavelength absorbed by the solution. Different colors have different wavelengths, such as blue 475 nanometers, green 510 nanometers, yellow 570 nanometers, orange 590 nanometers, and red 650 nanometers (What Wavelenght Goes With a Color?). A spectrophotometer contains a light source that is continuous in the visible region of the electromagnetic spectrum. The percentage of transmittance tells the amount of light transmitted and is related to the absorption level. Absorbance depends on the absorbing substance, its concentration, the path length, wavelength, identity of the solvent, and the temperature (Spectrophotometry).

The problem is solutions with unknown concentrations of substances have to be determined by using a standard curve developed from a known concentration of a substance. The Scientific Process is the idea that humans can discover things without depending on other knowledge sources and rules that are derived from a general principal can be used to make predictions (Colavito, 2010). The Spectrophotometer can be used to measure the wavelengths in the unknown concentration of substance to be compared to the wavelengths of known concentrations of substance. The absorbance of each wave length can be measured and compared to the standard measurements of wavelength to determine the concentration of the unknown substance. Some light is absorbed when the light of the wavelength is passed through the solution. Light that is not absorbed is transmitted. The spectrophotometer detects the light and expresses it as either absorbance (A) or a percentage of transmittance (%T). The lower the absorbance, the higher percentage of transmittance or the higher the absorbance, the lower the transmittance is expressed. Wavelength and color are correlated because for every range of wavelength, a color is observed. There is a higher absorbance with the higher concentration that results in a higher amount of light being absorbed. The lower the concentration has a higher transmittance with a lower amount of light being absorbed. Using the amount of absorbance from a set of standards from a known concentration of substance, a standard curve can be graphed and used to extrapolate and determine the unknown concentration of a substance.