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 7.56. A linear calibration curve can be constructed from this data as a plot of potential (in mV) vs. pBr. 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 0.7 mV and the potential reading for unknown 2 was 122.5 mV. Using the calibration curve you constructed above, determine the concentration of Br^- in each unknown solution

Explanation / Answer

slope = -61.3

y intercept = -56.196

For unknown 1 :

y = 0.7 mV

substitute the value of y in the equation to find out the value of x

y = -61.3x - 56.196

or, x = (0.7+56.196)/-61.3 = -0.93

log[Br-] = -0.93

or, [Br-] = 10^-0.93 = 0.117 M

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

unknown 2:

y = 122.5 mV

substitute the value of y in the equation to find out the value of x

y = -61.3x - 56.196

or, x = (122.5+56.196)/-61.3 = -2.92

log[Br-] = -2.92

or, [Br-] = 10^-2.92 = 0.0012 M

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

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