Homework Answers
Part a.
The electrode potential is inversely related to the pH of the solution.
i.e. Higher the pH, the smaller is the value of electrode potential.
In the same way, lower the pH, the greater is the value of electrode potential.
Therefore, when the pH of the solution is increased from 5.5 to 11.0, then the change in electrode potential < 0 (negative value).
Part b.
At pH =4, E = 200 mV
At pH = 7, E = 23 mV
Now, If E = 157 mV, then the pH of the solution will be in between 4 and 7, i.e. 4 < pH < 7
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7. (10 points) a) The selectivity coefficient for a Bromide ion-selective electrode is on 0.15. What...
Calibration data for a bromide ion‑selective electrode (ISE) was collected and recorded in the table. The...
Calibration data for a bromide ion‑selective electrode (ISE) was collected and recorded in the table. 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. Br-M Potential (mV 0.300 -21.6 0.0300 36.7 0.00300 96.5 0.000300...
Question 4 of 4 > Potential (my -21.9 Calibration data for a bromide ion-selective electrode (ISE) was collected...
Question 4 of 4 > Potential (my -21.9 Calibration data for a bromide ion-selective electrode (ISE) was collected and recorded in the table. 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. [Br"](M) 0.300...
Calibration data for a bromide ion-selective electrode (ISE) was collected and recorded below. The potential of...
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 [Br] (M) Potential (mV) 0.300 0.0300 0.00300 96.4 0.000300 155.1 0.0000300 224.8...
Potential (mV) [Br](M) 0.300 Calibration data for a bromide ion-selective electrode (ISE) was collected and recorded in...
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An ammonium ion selective electrode exhibits interference from lithium ions with a selectivity coefficient of 0.2. If a 0.10 M solution of ammonium has an electrode potential of 0.125 V what is the expected potential in a solution containing both 0.1 M ammonium and 0.1 M lithium? Recall that the Nernst equation for a cation selective electrode with interferent is Ecell L'002 Logho(a + Kb) where a and b are the activities(-concentrations) of the selective ion and interfering ion, respectively.
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A nitrate ion selective electrode is calibrated versus a Ag/AgCl reference electrode with a series of standards, producing the graph shown, including the regression equation. Is the slope within 10% of the expected value? (Yes, No or there is no 'expected value) Is the intercept within 10% of the expected value? (Yes, No or there is no 'expected' value) Calculate the molar concentration of NO3' in a solution which gives a potential of 38.4 mV (also using the same Ag/AgCl...
7) An ion selective electrode and reference electrode pair were placed in 100.00 mL of the...
7) An ion selective electrode and reference electrode pair were placed in 100.00 mL of the sample, and a reading of 21.6 mV was obtained. After the addition of 10.00 mL of a standard solution with a concentration of 100 ug/mL, the electrode pair gave a reading of 43.7 mV. The response slope (i.e., the slope of the line give by the equation E=mx+ constant, where x = log[ion]) was previously determined to be 57.8 mV. What is the sample...
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Question 4 of 4 > Potential (my -21.9 Calibration data for a bromide ion-selective electrode (ISE) was collected and recorded in the table. 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. [Br"](M) 0.300...
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 [Br] (M) Potential (mV) 0.300 0.0300 0.00300 96.4 0.000300 155.1 0.0000300 224.8...
Potential (mV) [Br](M) 0.300 Calibration data for a bromide ion-selective electrode (ISE) was collected and recorded in the table. 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. -21.2 0.0300 36.2 95.7 0.00300 0.000300...
The selectivity coefficient, KL.H' for a Li + ion selective electrode is 4 × 104, when the electrode is placed in 3.44 × 10-4 mol L-1 Li+ solution at pH 7.2, the potential is -0.333 V versus a saturated calomel electrode. What would be the potential if the pH were lowered to 1.1 and the ionic strength was kept constant?
An ammonium ion selective electrode exhibits interference from lithium ions with a selectivity coefficient of 0.2. If a 0.10 M solution of ammonium has an electrode potential of 0.125 V what is the expected potential in a solution containing both 0.1 M ammonium and 0.1 M lithium? Recall that the Nernst equation for a cation selective electrode with interferent is Ecell L'002 Logho(a + Kb) where a and b are the activities(-concentrations) of the selective ion and interfering ion, respectively.
A nitrate ion selective electrode is calibrated versus a Ag/AgCl reference electrode with a series of standards, producing the graph shown, including the regression equation. Is the slope within 10% of the expected value? (Yes, No or there is no 'expected value) Is the intercept within 10% of the expected value? (Yes, No or there is no 'expected' value) Calculate the molar concentration of NO3' in a solution which gives a potential of 38.4 mV (also using the same Ag/AgCl...
7) An ion selective electrode and reference electrode pair were placed in 100.00 mL of the sample, and a reading of 21.6 mV was obtained. After the addition of 10.00 mL of a standard solution with a concentration of 100 ug/mL, the electrode pair gave a reading of 43.7 mV. The response slope (i.e., the slope of the line give by the equation E=mx+ constant, where x = log[ion]) was previously determined to be 57.8 mV. What is the sample...
(5) The following data represent the potentials of a fluoride ion-selective electrode vs SCE for several solutions. All solutions are made up in a way to control their pH and ionic strength, and contain added EDTA. Prepare an excel plot of the measured potential vs pF based on this information and determine the concentration of fluoride in each unknown solution. 5 Solution (M) Potential (mv) 5.0 x 102 -22.4 .0 x 103 36.8 5.0 x 104 96.0 5.0 x 10-...
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