Please answer and show all work (including how to plot the data on Microsoft Exc

Question

Please answer and show all work (including how to plot the data on Microsoft Excel.

Calibration data for a bromide ion-selective electrode (ISE) was collected and recorded below. The potential of the ISE was measured against a saturated calomel electrode (SCE). All solutions were buffered at a pH of 7.56. A linear calibration curve can be constructed from this data as a plot of potential (in mV) vs. log[Br^-]. Determine the slope and y-intercept of such a plot of the calibration data given. Two unknown solutions were tested for [Br^-] using the same bromide ISE. The potential reading for unknown 1 was 29.5 mV and the potential reading for unknown 2 was 193.0 mV. Using the calibration curve, you constructed above, determine the concentration of Br^- in each unknown solution.

Explanation / Answer

y = -61.18x - 55.99

Slope = -61.18

Intercept = -55.99

For unknown 1 :

y = 29.5 mV

x = (29.5 +55.99)/-61.18 =-1.397

[Br-] = 10^-1.397 = 0.04 M

-------------------------------------------------------

For unknown 2 :

y = 193 mV

x = (193 +55.99)/-61.18 =-4.069

[Br-] = 10^-4.069 = 8.53*10^-5 M

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