Equilibrium concentrations, oxygen

C12-0059. One of the reasons that different aquatic life-forms thrive in water of different temperatures is the variation with temperature in the concentration of dissolved oxygen. Using data in Table 12-2. calculate the percentage change in the equilibrium oxygen concentration when water warms from 0.0 °C to 25.0 °C. 

The equilibrium oxygen concentration Cl is given by the combination of Henry s law and the Ideal Gas Law equation where... 

The equilibrium amount of nitric oxide (0.12%) demands for its formation the entire available amount of oxygen (0.6%). However, in reality the formation of 0.12% NO merely causes a decrease in H20 from 24.2% to 24.1% and an increase in H2 from 4.3% to 4.4% the equilibrium oxygen concentration changes by less than 5% of its magnitude. 

Since the concentrations inside the membrane are generally not known, we can express the equilibrium oxygen concentration at steady state using the diffusion-reaction relations of Eqs. (9.192)—(9.194) assuming that Dc = Dbc, we have... 

DC, the product of the effective diffusion coefficient of oxygen (cm2 s-1), and the equilibrium oxygen concentration (moles cm-3 atm-1) in the catalyst layer at the interface with the backing (GDL),... 

The flux of oxygen can be in or out of the ocean. The oxygen partial pressure in the atmosphere is 0.20 atm and Henry s Law constant is 1.26 x 10" M/atm. (a) As a result of photosynthesis, the nitrate concentration in seawater originally in equilibrium with the atmosphere has decreased by lOfiM. What is the new (non-equilibrium) oxygen concentration ... 

The solubility of oxygen in water with a salt content up to 1 mol L is only dependent on the temperature. The oxygen concentrations in equilibrium with air amount to (in mg L- ) 0°C, 14 10°C, 11 20°C, 9 and 30°C, 7. The depth of water has no effect in the case of ships. In Hamburg harbor in summer, 7.3 mg L are measured in depths up to 7 m. The value can be much lower in polluted harbors and even fall to zero [8]. In the open sea, constant values are found at depths of up to 20 m. With increasing depth, the Oj content in oceans with low flow rates decreases [12] but hardly changes at all with depth in the North Sea [13]. 

C oxygen concentration in equilibrium with the partial pressure of oxygen, kg/m ... 

CAL Oxygen concentration in equilibrium with liquid phase at the interface, kmol/m3 CAL Oxygen concentration in the bulk of liquid, kmol/m3 a Interfacial area in surface area of bubbles per unit volume of broth, m2/m3 PQ, Oxygen partial pressure at the interface, atm H Henry s law constant, atm... 

C Oxygen concentration at equilibrium with liquid phase, mmolT-1... 

C Oxygen concentration in equilibrium with liquid phase at the interface, kmol-m... 

The simple equation for oxygen transfer rate is based on driving forces existing for the equilibrium value for oxygen concentration and the dissolved oxygen available in the liquid phase. That is ... 

The oxygen transfer rate is calculated based on oxygen concentration gradient, by determination of the oxygen level in the liquid phase and the equilibrium value. 

With an assumption of oxygen concentration at the interface, equilibrium with liquid phase is 6 ppm, the oxygen transfer rate is calculated. 

It should be noted however that the method related to the measurements of equilibrium or stationary oxygen concentrations by means of sensors is not always applicable and convenient even in this particular case. Sometimes too much time is required to conduct these measure-... 

C Q2 is the dissolved oxygen concentration in equilibrium with the oxygen in the air supply at the operating pressure and temperature of the system. Since the dissolved oxygen concentration is measured as percent of saturation. DO (%), the above equation can be rewritten as... 

In the case of LNT, different proposals have been advanced to explain the mechanisms governing the NO, release. Recent papers suggested that the NO release is provoked by the heat generated upon the reducing switch (thermal release) [40], by the decrease of the gas-phase oxygen concentration that destabilizes the stored nitrates [41], by spillover and reduction of N02 onto reduced Pt sites or by the establishment of a net reducing environment, which decreases the equilibrium stability of nitrates [12,42,43],... 

---