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The table below shows the amount of 0.531 m standard x added to 50.0 ml sample and the corresponding HPLC readings. Find the concentration of x in the sample. Neglect the change in volume due to the addition of the standard. vstd (microliter): 0 100.0 200.0 300.0 400.0 peak Area: 1084 1844 2473 3266 4010 a) 3.21 x 10^-4 M B) 3.21 x 10^-4 M C) 1.58 x 10^-3 m d) 3.75 x 10^-3 m
Accepted Answer
This problem involves a standard addition method, which is a common technique in analytical chemistry to determine the concentration of an analyte in a sample. Here's how to solve it:
1. Plot the Data: Plot the peak area (y-axis) against the volume of standard X added (x-axis). You should get a linear relationship.
2. Find the Equation of the Line: Determine the slope and intercept of the best-fit line through the plotted points. This equation will be in the form:
Peak Area = (slope
VSTD) + intercept
3. Calculate the Concentration: The intercept of the line represents the peak area due to the analyte in the original sample. The slope of the line represents the change in peak area per microliter of standard added. To find the concentration of X in the sample, use the following formula:
[X] = (intercept
[standard X]) / (slope
sample volume)
where:
[X] is the concentration of X in the sample
[standard X] is the concentration of the standard solution (0.531 M)
sample volume is 50.0 mL = 0.050 L
Note: The question asks you to neglect the change in volume due to the addition of the standard. This is a common simplification, but it's important to recognize that in reality, the volume does change slightly.
Let me know if you'd like me to help you calculate the specific concentration using the given data. I'll need the slope and intercept from the plotted data.
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