Why do you draw a linear graph of absorbance versus concentration even though your experimental values deviated slightly from a straight line?
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When drawing a linear graph of absorbance versus concentration, we aim to establish a relationship between these two variables. This relationship is often expressed through a mathematical equation, specifically the Beer-Lambert Law, which states that absorbance is directly proportional to the concentration of a substance in a solution.
However, it's important to note that experimental values may not always perfectly align in a straight line due to various factors, such as measurement errors or experimental limitations. These deviations can arise from issues such as instrumental inaccuracies, fluctuating environmental conditions, or limitations in the accuracy of the analytical technique employed.
Despite these slight discrepancies, we still draw a linear graph for several reasons:
1. Visualizing the trend: A linear graph provides a visual representation of the general trend between absorbance and concentration. It allows us to observe any patterns or trends in the data, even if individual data points deviate slightly from the ideal straight line.
2. Mathematical approximation: By drawing a linear graph, we can approximate the relationship between absorbance and concentration through a linear equation. While individual data points may not lie exactly on the line, the drawn line serves as an average or best-fit representation of the overall relationship.
3. Extrapolation and interpolation: A linear graph allows us to estimate or predict the absorbance values for concentrations that are not present in the experimental data. We can extrapolate beyond the measured concentrations or interpolate within the concentration range to estimate the absorbance values.
4. Simplification and ease of interpretation: A linear relationship is often easier to interpret and analyze than more complex relationships. It provides a straightforward understanding of the relationship between absorbance and concentration, making it more feasible for practical applications and mathematical calculations.
In summary, despite slight deviations from a straight line, drawing a linear graph of absorbance versus concentration allows us to effectively understand and approximate the relationship between these variables, facilitate data interpretation, and make valuable predictions or estimations.