Question

Tap water which is commonly used in fish pond, may contain chlorine (Cl2). To allow the fish to live healthily, the chlorine can be pre-treated using sodium thiosulfate (Na2S2O3). Removal of chlorine depends on the assumed conversion in 1 m3 of rectangular fish tank (pond) volume. Water (H2O) is in excess state of having 4 ppm chlorine. Referring to the findings by Cao et al. (2007), the liquid-phase reaction is zero order with respect to water whilst the rests are first order rate of reaction. It is also mentioned that the rate of reaction constant is 4.5208 X 103 L/mol/s. (a) Propose the complete chemical reaction for the reaction taking place in the fish tank. Clearly state the reactants and products and elaborate on the specific roles of the reactants during the treatment. (7 marks) (b) Qualitatively assess the perfectly mixed batch reactor design system for the chlorine pre-treatment over the change of time with respect to conversion in an assumed X of up to 60%. You may write down in words your possible assessment strategies pointing out the solution steps.