A calibration curve for CuSO4 at 635 nm yields a straight line described by the
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Question
A calibration curve for CuSO4 at 635 nm yields a straight line described by the equation y = 3.885 x + 1.050. If the concentration of a sample of CuSO4 is 0.605 M, what is the predicted value of its absorbance? Provide your response to three digits after the decimal.
D Question 2 2 pts A calibration curve for CuSO4 at 635 nm yields a straight line described by the equation y 3.885 x 1.050. If the concentration of a sample of CuSO4 is 0.605 M, what is the predicted value of its absorbance? Provide your response to three digits after the decimal. Question 3 D 2 pts Distilled water (1.903 mL) is added to a cuvette for calibration of the SpectroVis. 3 aliquots, each 421.433 HL in volume, of 0.40 M CuSO4 are then added sequentially to the water in the cuvette. What is [CuSO4] after the third aliquot is added? Provide your response to three digits after the decimal.Explanation / Answer
Ans. In the absorbance vs concentration graph, Y-axis indicates absorbance and X-axis depicts concentration.
The calibration curve (straight line) equation is given by-
A = m X + b - equation 1
Where, A = absorbance, ; m = slope ; X = concentration corresponding to A ; and
b = intercept.
That is, according to the trendline equation y = 3.885 x + 1.050 obtained from the graph, one absorbance unit on y-axis (i.e. y= 1.000) is equal to 3.885 units on X-axis (i.e. 3.885 x) plus 1.050. To be noted, 1.050 is the intercept and a constant.
Now,
Given, [CuSO4] = 0.605 M
Let’s assume that it’s corresponding absorbance = A
Putting the absorbance value A (i.e. y = A) and concentration value 0.605 (i.e. x = 0.605) in trendline equation “y = 3.885 x + 1.050”-
A = 3.885 (0.605) + 1.050 ; [ y = A ; and x= 0.605 ]
Or, A = 3.400425
Thus, absorbance A is equal to 3.400425 for the given concentration.
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