# 5 10 15 20 25 00 20 40 60 80 100 120 fx r² 0

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05101520250.02.04.06.08.010.012.0f(x) = R² = 0Concentration vs. AbsorbanceConcentration (ppm)AbsorbanceAveraging rounds the numbers i.e. the R2and equation, up. This is less accurate. It changes the value we would get if we were to look for the concentration of an unknown.4.Limit of Detection = (3sm)= (3×0.000160.0360)= 0.00133Limit of Quantification = (10sm)= (10×0.000160.360)=0.0444The linear range is from 0ppm to 20ppm as shown in the graph5.And 6GroupExternal MethodStandard Addition Method19.469.855210.19.272315.613.1849.094.97550.5814.004625.317.49711.110.39810.311.27
7.t-Test: Paired Two Sample for MeansVariable 1Variable2Mean13.6433333311.92167Variance37.481666679.347137Observations66Pearson Correlation0.977638859Hypothesized Mean Difference0df5t Stat1.318467853P(T<=t) one-tail0.122254948t Critical one-tail2.015048373P(T<=t) two-tail0.244509897t Critical two-tail2.570581836As shown with the t-test, the tcalculatedis 1.3185 which is less than 2.57058 meaning that the meansare not too different.8. external method uses know quantities of the analyte to get absorption. A graph is drawn and the concentration of the unknown is found by using the equation of the line. For standard addition, a known quantity is added to the unknown and for the Internal method, a known amount of the compound is added, this compound should be different from the analyte. From there the concentration of the unknown can be found.
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