Suppose you generate the following spectroscopic data with five solutions of kno

Question

Suppose you generate the following spectroscopic data with five solutions of known concentration.

Conc                      Absorbance

.0135                          .1277

.0270                          .2374

.0540                          .4872

.108                             1.006

.216                            1.968

What is the slope of the linear regression line formed by these points?

What is the intercept of the linear regression line?

What is the concentration of a solution with an absorbance of 0.683?

What is the concentration of a solution with an absorbance of 1.177?

Explanation / Answer

Answer: By plotting the graph (calibration plot) between concentartion vs absorbance regression line equation was obtained as: y = 9.1419x + (8x10-5) .........equation (1)

BY COMPARING WITH STARIGHT LINE EQUATION: y = mx +c

[y is absorbance; m is slope; x is concentration and c is intercept]

Ans (a) we get, slope = 9.1419

Ans (b) intercept = 8x10-5 = 0.00008

Ans (c) By putting value of absorbance as 0.683 in y in equation (1) we get concentration.

0.683 = 9.1419x + 0.00008

x= (0.683-0.00008)/9.1419 = 0.0747 unit

Ans (d)

By putting value of absorbance as 1.177 in y in equation (1) we get concentration.

1.177 = 9.1419x + 0.00008

x= (1.177-0.00008)/9.1419 = 0.1287 unit

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