Please help, I only need help on part (c). I cannot figure out how to reach that
ID: 975905 • Letter: P
Question
Please help, I only need help on part (c). I cannot figure out how to reach that answer. Everything else has been answered.
The following data were obtained when a Ca2+ ion-selective electrode was immersed standard solutions whose ionic strength was constant at 2.0 M.
(a) Prepare a calibration curve and find the least-squares slope and intercept.
(b) Calculate the value of in the equation below.
NOTE: convert the slope from part (a) to Volts.
0.951 (3 decimal places)
(c) For a measured potential, the calibration curve gives us log[Ca2+]. We can compute [Ca2+] = 10log[Ca2+]. Calculate [Ca2+] of a sample that gave a reading of 26.9 mV in four replicate measurements.
Explanation / Answer
A plot of log (Ca+2) Vs E (mV) is shown below
the slope is 28.14 and intercept is 51.09
slope = 28.14*10-3V
Slope =(0.05916/2)*B= 28.14*10-3
B = 28.14*10-3*2/0.05916
B= 0.9513
c) given E= -26.9 mV
-26.9= 51.09 +28.14 log (Ca+2)
-77.99 = 28.14 log (Ca+2)
Ca+2= 0.062568