Question

A UV/vis light absorbance spectrophotometer produced the following linear calibration equation for a given standard,

A=0.653C+0.0342

where C is the molar concentration and A is the absorbance. The detector's lifetime was running out, so the lab manager replaced the detector.

Before the lab manager properly aligned the detector and diffraction grating, a student measured different standard concentrations and got the data in the second column of the table. The lab manager aligned the detector and diffraction grating and alerted the student that the data was probably unreliable. The student retook the measuresurements and got the data in the third column of the table.

Find the linear calibration equation and the square of the correlation coefficient, R^2, for each set of measurements.

Before alignment:

A=

C+=

R²=

After alignment:

A=

C+=

R²=

Concentration (M)	Absorbance before alignment	Absorbance after alignment
0	0.0540	0.0351
0.10	0.1258	0.1000
0.20	0.1855	0.1677
0.30	0.2445	0.2303
0.40	0.2991	0.3054
0.50	0.2925	0.3610
0.60	0.3052	0.4068
0.70	0.3613	0.4731
0.80	0.4829	0.5478
0.90	0.5552	0.6279
1.0	0.6525	0.6887

Answer 1