Chapter 4 - Jacobs University

Chapter 2
Experimental
To this solution, 82.5 mL of 4M HCl was added in 1-mL portions over 10min, with vigorous
stirring. Solution A then was added to solution B, and the pH was adjusted to between 5 and 6 by
addition of the 4M HCl solution for 100 min. 45 g of Solid KCl was the added to the resulting
solution and after 15min stirring the precipitate was collected. Purification was achieved by
dissolving the product in 450 mL of water. The insoluble materials were rapidly removed by
filtration on a frit, and the salt was precipitated again by adding 20g of solid KCl. The precipitate
was separated by filtration, washed with 2M KCl solutions and air-dried. 12
2.2.14 Synthesis of K 8 [g-SiW 10 O 36 ]×20H 2 O
15 g of K salt of b 2 -SiW 11 was dissolved in 400 mL of distilled water. Insoluble impurity was
removed by filtering on a frit containing celite. The pH of the solution was adjusted to 8.80 by
addition of a 2 M aqueous solution of K 2 CO 3 . The pH of this solution was kept at this value for
exactly 16 minutes. 20 gm of KCl was added to it and stirred for 10 minutes. The pH was still
maintained at 8.80 by adding 2 M aqueous solution of K 2 CO 3 solution. It was characterized using
FTIR spectroscopy. 13
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