Calibration data for a bromide ion-selective electrode (ISE) was collected and r

Question

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 7.58. 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 calibrates data given. slope = -216.6 y- intercept = Two unknown solutions were tested for [Br] using the same bromide ISE .The potential reading 1 was -20.1 mV and the potential reading for unknown 2 was 125 3 mV Using the castration cm constructed above, determine the concentration of Br^-in each unknown solution. Unknown 1 [Br^-] = M Unknown 2 [Br^-] = M

Explanation / Answer

a plot of log(Br-) vs Potential is drawn and shown below

The equation of best fit is potential (mV)=-61.27log(Br-)-63.99 it is in the form y= mx+c. m is slope

The slope of the plot is - 61.27 , y intercepy is -63.99 mV

for potential of -20.1 mV, -20.1= -61.27log(Br-)- 63.99

log (Br-)= -43.89/61.27, [Br-] =0.1921 M

for potential of 125.3 mv,

125.3= -61.27 log[Br-]- 63.99

125.3+63.99 = -61.27*log[Br-]

[Br-]=0.000817 M

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.