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Beer's law states that there is a linear relationship between the concentration and the absorbance of the solution, enabling the concentration of a solution to be calculated by measuring its absorbance. Sketch the Beer's law plot of absorbance versus concentration.

a) Concentration has no effect on absorbance.
b) Plotting absorbance against time is more accurate.
c) The relationship is exponential, not linear.
d) Linearly increase both concentration and absorbance.

1 Answer

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Final answer:

Beer's Law indicates a linear relationship between absorbance and concentration, which is crucial for determining the concentrations of various compounds in biochemistry using UV-visible spectroscopy.

Step-by-step explanation:

Beer's Law states that there is a linear relationship between the concentration of a solution and its absorbance. When plotted on a graph with absorbance on the y-axis and concentration on the x-axis, the expected result is a straight line, indicating that as concentration increases, absorbance also increases in a proportional manner. This is important in fields such as biochemistry where measurements of compounds like DNA, RNA, or protein concentrations are commonly determined using UV-visible spectroscopy and based on this principle.

For example, the concentration of DNA can be estimated by measuring its absorbance at 260nm. The Beer-Lambert law for this case is represented as Absorbance (at 260nm) = ε*c*l, where ε is the absorption coefficient, c is the concentration, and l is the path length. Similarly, protein concentrations can be determined through assays that produce a color change correlating to protein quantity, with the relationship between protein concentration and absorbance being depicted on a standard curve.

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