What is the likely source of error from reading a graph where the absorbance (y-axis) versus concentration (x-axis) shows non-deal behaviour. The graph is going in what looks like a line of best fit but then curves off a the end. At the end of the graph there is a curve and it kind of dips down.
The likely source of error for a graph showing non-ideal behavior, where the absorbance versus concentration curve deviates from a straight line and curves off at the end, can be due to a few reasons. Here are some possibilities to consider:
1. Saturation of absorbance: If the curve flattens or dips down at high concentrations, it may suggest that the method used to measure absorbance has reached its limit or saturation point. At higher concentrations, the absorbing species might be too concentrated to allow accurate measurement using the specific analytical technique.
2. Chemical reaction: It is possible that for high concentrations, the analyte (substance being measured) undergoes a chemical reaction that alters its absorption properties. This can result in nonlinear behavior or deviation from the expected linear relationship.
3. Instrument or experimental error: Non-ideal behavior can also arise from instrumental limitations or experimental mistakes such as incorrect calibration, sample preparation errors, or inconsistent measurements.
To determine the actual source of error and address it properly, here are a few steps to consider:
1. Validate the calibration: Make sure the instrument used for measuring absorbance is correctly calibrated. Check if the calibration curve covers the entire concentration range being analyzed. If not, recalibrate the instrument accordingly.
2. Sample dilution: If the curve deviates at higher concentrations, try diluting the samples and measuring again within the linear range of the instrument.
3. Control experiments: Perform control experiments to differentiate inherent chemical behavior from experimental or instrumental errors. This can involve running blank samples without the analyte and checking for any unexpected absorbance values.
4. Verify with different methods: Confirm the results obtained with alternate analytical techniques to cross-validate your findings. Different methods may have different limitations and can help identify potential errors.
If the deviations in the graph persist even after taking these steps, it might be necessary to consult an expert or consider alternative approaches to obtain accurate measurements.