Labs 5-8 Overview Study Guide Cellular Respiration, Enzymes, Microscopy, Cellular Transport, and Spectrophotometry

Vocabulary terms and definitions covering principles of spectrophotometry, Beer's Law, standard curve generation, and food dye absorption analysis.

Spectrophotometer

An instrument that measures how much light a sample absorbs by comparing the intensity of light before and after it passes through the sample.

Absorbance

A measure of how much light is absorbed by a sample as light passes through it, where higher absorbance indicates more light is being retained by the sample.

Transmittance

The percentage of light that passes through a sample, calculated as $\text{\%T} = (\text{transmitted light} / \text{incident light}) \times 100$.

Cuvette

A small, transparent container used to hold liquid samples in a spectrophotometer.

Beer's Law

The principle stating that absorbance increases proportionally with concentration in a solution, allowing scientists to calculate unknown concentrations using measured absorbance values.

Standard Curve

A graph showing the relationship between known concentrations of a solution and their corresponding absorbance values, used to determine the concentration of unknown samples.

Blanking

The process of auto-zeroing the spectrophotometer using a cuvette filled only with solvent to calibrate the machine and ensure that only the absorbance of the solute is measured.

$$A_{\max}$$

The wavelength of maximum absorbance, representing the specific wavelength at which a sample absorbs the most light.

Dilution

A process of decreasing the concentration of solute in a solution, typically by adding more solvent.

Absorption Spectrum

A graph or pattern of light absorption across wavelengths that creates a unique "fingerprint" for a specific chemical.

FD&C Dyes

Federally approved food dyes—including Red 40, Red 3, Yellow 5, Yellow 6, Blue 1, and Blue 2—that are used to artificially color foods, drugs, and cosmetics, each possessing an identifiable absorption spectrum and peak.