(2) (a) Calculate Ksp for MX 2 in the system:
M|MX 2 (saturated), X– (0.400 M)|H 2 (1 atmosphere) Pt(b) Calculate for the 1/2-cell reaction:(3) A 0.2g sample of toothpaste containing fluoride was treated with 50 cm^3 of a suitable buffer solution
and diluted to 100 cm^3. Using a fluoride ion-selective electrode, a 25.00 cm^3 aliquot of this solution
gave cell potentials of –155.3 mV before and –176.2 mV after spiking with 0.1 cm^3 of a 0.5 mg cm–^3
fluoride standard. Calculate the pF– corresponding to each cell potential and the percentage by weight
of fluoride in the toothpaste.
(4) Plot the titration curve in the vicinity of the end-point and its first and second derivatives from the
following data and compare the end-point values:
Burette reading/cm^3 Cell potential/mV
47.60 372
47.70 384
47.80 401
47.90 512
48.00 732
48.10 748
48.20 756(5) An organic acid (0.6079 g) was dissolved in 45.67 cm^3 of an NaOH solution, and the excess base
titrated with 3.25 cm^3 of 0.12 M HCl. In a standardizing titration, 39.33 cm^3 of the NaOH solution was
equivalent to 31.69 cm^3 of the 0.12 M HCl. Calculate the molecular weight of the unknown acid.
(6) The iron in a 0.100 g sample was converted quantitatively to Fe(III) and titrated coulometrically
with electrogenerated Ti(III). A current of 1.567 mA for 123.0 seconds was required to reach the end-
point. Calculate the percentage of iron in the sample. (1 farad = 96 485 coulombs mol–^1 )
(7) Sketch the shape of the titration curve for the following conductometric titrations:
(a) silver acetate vs. lithium chloride(b) ammonium chloride vs. sodium hydroxide(c) sulphuric acid in glacial acetic acid vs. sodium hydroxide(d) a bromide solution vs. silver nitrate(Use the data in Table 6.6).