CY407 Mons.'13 Assignment 2 - due on 27-9-13.

General Instructions:

Summissions must be handwritten on A4 size papers stapled together with only your name and roll number on the first page. Do not bind and do not submit in folders.

Programs should conform to FORTRAN-77 standard.

Write neatly (capital letters for statements) using a coding sheet similar to the one here -you may print this or make one yourself!

Problem: The dissociation of a weak monoprotic acid in water is governed by the equilibria:
HA = H⁺ + A^-        K_a = [H⁺] [A^-] / [HA]
H₂O = H⁺ + OH^-         K_w = [H⁺] [OH^-] = 1.0 x 10^-14

We, therefore, have for the total concentration of the acid,
C_t = [A^-] + [HA] (mass balance) and
[H⁺] = [A^-] + [OH^-] (charge balance).

Set up a cubic equation to determine [H⁺], given pK_a of the acid and its total concentration. Solve this equation using the Newton-Raphson method to obtain the equilibrium pH of a 1.0 x 10^-6 M acetic acid solution. The pK_a for acetic acid is 4.7.

Your report should contain the equation, the Newton Raphson iteration formula for solving that equation, the computer program, the starting value used for the iteration, number of iterations done and converged value for [H⁺] and the pH.

Be original!     Plagiarised submissions, when detected, will be given failing marks!!