1) A calibration curve for CuSO4 at 655 nm yields a straight line described by t

Question

1) A calibration curve for CuSO4 at 655 nm yields a straight line described by the equation y = 2.821 x + 0.673. If the measured absorbance for a solution of unknown concentration of CuSO4 is 0.366, what is the concentration of the CuSO4 solution? Provide your response to three digits after the decimal. _____ M

2) A calibration curve for CuSO4 at 875 nm yields a straight line described by the equation y = 3.295 x + 0.233. If the concentration of a sample of CuSO4 is 0.273 M, what is the predicted value of its absorbance? Provide your response to three digits after the decimal.

3) The reported molar absorptivity of CuSO4 is 0.524 L mol-1 cm-1. If a solution of CuSO4displays an absorbance of 0.063 in a cuvette that is 1.472 cm in length, what is the concentration of the CuSO4 solution? Report your response to three digits after the decimal. _____ M

Explanation / Answer

The equation for calibration chart is concentration = 2.821* absorbance +0.673

given absorbance =0.366, concentration =2.821*0.366+0.673 =1.705M

2. given concentratiopn = 3.295*absorbance+ 0.233

0.273= 3.295* absorbance+0.233

absorbance = (0.273-0.233)/3.295 = 0.01214

3. from A= ebC, e= 0.525 L/molcm. A= 0.063 and L= 1.472

C = A/eb = 0.063/(0.525*1.472)=0.0815M

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