Continuity equation, averaged, suspensions

A mathematical model for styrene polymerization, based on free-radical kinetics, accounts for changes in termination coefficient with increasing conversion by an empirical function of viscosity at the polymerization temperature. Solution of the differential equations results in an expression that calculates the weight fraction of polymer of selected chain lengths. Conversions, and number, weight, and Z molecular-weight averages are also predicted as a function of time. The model was tested on peroxide-initiated suspension polymerizations and also on batch and continuous thermally initiated bulk polymerizations. 

This chapter presents our recent efforts to develop and calibrate a sand transport model that is suited for practical applications but contains the basic mechanics of sand suspension and bedload movement on beaches. The hydrodynamic input required for the sand transport model is limited to the variables of irregular waves and currents which can be predicted efficiently and fairly accurately using a combined wave and current model based on time-averaged continuity, momentum, and energy equations. More advanced but computationally-demanding wave and current models may not improve the accuracy of the sand transport model with errors of a factor of about 2. Moreover, practical coastal sediment problems require the prediction of sediment transport rates for a duration of days to years. The computational efficiency is hence essential for practical applications. 

Investigating the reaction between hydroxylammonium chloride and iodine Weigh out accurately about 0.86 g of purest HO.NH3.CI and make up to 250 cm in a volumetric flask. Pipette 25.0 cm aliquot of the solution into a conical flask and dilute to about 150 cm Warm the solution on a hot plate, fitted with a magnetic stirrer. Add 0.15 g purest MgO (used to avoid acidity of the solution) and add slowly (standardised) 0.05 M iodine solution from a burette keeping the suspension warm. When the colour of iodine fades slowly, add 2 cm of freshly prepared starch solution to the conical flask and continue the titration slowly until the blue colour of the starch/iodine adsorption complex persists for 30 seconds. From the average of two concordant titres, deduce the molar ratio I2 to (HO.NH3) and hence an equation representing the reaction, based on changes in oxidation numbers. 

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