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Treatment of Results Part 1 Obtaining a calibration plot Salicylic Acid Solution /cm3 Concentration /mol.dm-3 Absorbance A 0.0 0.000 0.002 B 0.5 0.048 0.301 C 1.0 0.096 0.487 D 1.5 0.144 0.715 E 2.0 0.192 0.923 F 2.5 0.240 1.184 To calculate the above concentrations, it is required to use the volumes of salicylic acid as shown above, using the formula below: Concentration = weight of tablet specified on container x volume of salicylic acid solution volume of total solution total volume of standard solution Therefore the concentration for 0.5cm3 salicylic acid solution is: = 300 x 0.5 250 12.5 = 0.048 mol.dm-3 These steps are repeated to calculate the other concentrations, each time changing the volume of salicylic acid solution used. Calculating the least squares regression line xi yi xi-x (xi-x)2 yi-y (yi-y)2 (xi-x)(yi-y) 1 0.000 0.002 -0.12 0.0144 -0.60 0.3600 0.0720 2 0.048 0.301 -0.072 0.0052 -0.55 0.3069 0.0399 3 0.096 0.487 -0.024 0.0006 -0.12 0.0132 0.0028 4 0.144 0.715 0.024 0.0006 0.11 0.0128 0.0027 5 0.192 0.923 0.072 0.0052 0.32 0.1030 0.0231 6 0.240 1.184 0.12 0.0144 0.58 0.3387 0.0698 0.72 3.612 0 0.0403 -0.25 1.1347 0.2103 x = 0.72 = 0.12 6 y = 3.612 = 0.602 6 The equation for the least squares regression is in the algebraic form: y = a + bx where a is the intercept of the line on the y-axis and b is the slope of the line. [1] [2] b = 0.2103 = 5.2184 0.0403 a = 0.602 - (5.2184 x 0.12) = -0.0242 Therefore the equation for...

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