Mass balance chemical reactions

Mass balance chemical reactions do not create or annihilate matter but only displace it. 

If a balanced chemical reaction involves more than one reagent, one of them will be the reference limiting reagent which will define the scale of the entire reaction. The numerator in the stoichiometric factor term takes into account the sum of the masses of all excess reagents used as appropriate. For any balanced chemical reaction in which all byproducts are identified, equation (4.1) maybe used to determine RME under a variety of scenarios. 

In the Surface Chemkin formalism, surface processes are written as balanced chemical reactions governed by the law of mass-action kinetics. The framework was developed to provide a very general way to describe heterogeneous processes. In this section many of the standard surface rate expressions are introduced. The connection between these common forms and the explicit mass-action kinetics approach is shown in each case. 

Molar mass balance The situation in which the measured increase in moles of degradation product(s) is equivalent to that predicted via a balanced chemical reaction from the number of moles of parent consumed. For a degradation reaction ... 

Classical chemical reaction engineering provides mathematical concepts to describe the ideal (and real) mass balances and reaction kinetics of commonly used reactor types that include discontinuous batch, mixed flow, plug flow, batch recirculation systems and staged or cascade reactor configurations (Levenspiel, 1996). Mixed flow reactors are sometimes referred to as continuously stirred tank reactors (CSTRs). The different reactor types are shown schematically in Fig. 8-1. All these reactor types and configurations are amenable to photochemical reaction engineering. 

The ferrous is oxidized to the ferric form from an oxidation state of +2 to +3. The difference between 2 and 3 is 1, and because there are 4 atoms of Fe, the amount of electrons involved is 1 x 4 = 4. The equivalent mass of Fe(OH)2 is then 4Fe(OH)2/4. Note that the coefficient 4 has been included in the calculation. This is so, because in order to get the total number of electrons involved, the coefficient must be included. The electrons involved are not only for the electrons in a molecule but for the electrons in all the molecules of the balanced chemical reaction, and, therefore must account for the coefficient of the term. For oxygen, the number of moles electrons involved will also be found to be 4 thus, the equivalent mass of oxygen is O2/4. 

Each term of a balanced chemical reaction, represents the mass of a participating substance. Thus, the general formula for finding the equivalent mass of a substance is... 

Example 5 Water containing 2.5 moles of calcium bicarbonate and 1.5 moles of calcium sulfate is softened using lime and soda ash. How many grams of calcium carbonate solids are produced (a) using the method of equivalent masses and (b) using the balanced chemical reaction Pertinent reactions are as follows ... 

For emphasis, we make the following summary For the hardness ions or associated species, the equivalent mass is obtained by dividing the molecular mass by the total number of valences of the positive or negative charges of the species, irrespective of the coefficient for all other species, the equivalent mass must be deduced from the balanced chemical reaction. 

Ca(OH)2 is actually slaked time CaO + H2O. Note that in order to find the equivalent masses, the same number of molecules of alum in the balanced chemical reaction as used in Equation (12.46) should be used in Eqs. (12.47) and (12.48) otherwise, the equivalent masses obtained are equivalent to each other. From the reactions, the equivalent mass of time (CaO) is 3CaO/6 = 28.05 and that of calcium carbonate is 3CaC03/6 = 50. 

Reaction equations (by which we mean a balanced [mass, charge] chemical reaction) should be numbered, if reference is made to them in the text, by Arabic numbers enclosed in parentheses, e.g., (1), written to the right of the... 

Now, I know that the balanced chemical reaction is based on a molar ratio, not a mass ratio, so I will need to change 2.00 grams of magnesium into moles of magnesium using the calculation from Lesson 7-2. I divide the mass of my sample by the molar mass of magnesium (24.3 g/mole), which I can find on the periodic table. 

The basis of the flow models are ordinary differential mass balances for each component on either side of the membrane. The mechanism for permeation is substituted in the mass balances. When reaction occurs the kinetic expression is also added to the balances. The chemical reaction is assumed to take place in... 

Equation 2.2.6 is the mathematical condition for a balanced chemical reaction. Show that the total mass is conserved when this relation is applied. Show that for a batch reactor M(0) = M f). Show that for steady-flow reactor, the mass flow rates at the reactor inlet and outlet are identical. 

As you review this problem, note that nitrogen and hydrogen are related in terms of moles, not mass. In chemical reactions, when substances react, their particles react. Ammonia gas is synthesized from nitrogen gas and hydrogen gas according to the balanced chemical equation below. 

In a 1-L beaker, 203 mL of 0.307 A7 ammonium chromate was mixed with 137 mL of 0.269 A7chromium(lll) nitrite to produce ammonium nitrite and chromium(lll) chromate. Write the balanced chemical reaction occurring here. If the percent yield of the reaction was 88.0%, what mass of chromium(lll) chromate was isolated ... 

Given the "balanced chemical reaction" for the production of S mores from CTQ 7, calculate the mass of S mores that can be made from 416 pounds of chocolate bars, 142 pounds of graham crackers, and 58.2 pounds of marshmallows. 

If no chemical reaction takes place, the balancing eqnations for mass and amount of substance may also be formulated for each constituent molecular species. This is referred to as a component balance. Chemical reactions are incorporated into the component balance by means of source and drain terms. 

Other details such as process flow diagram, mass and energy balance Chemical reaction details Operating/control philosophy Equipment/instrument specification Site data and plant layout Alarm/trip/relief valve set values MSDS and material property... 

Now, [A]( and [B]( imply that the rate is dependent on the instantaneous concentrations of A and B at any time. Notice that the rate is also written in terms of the instantaneous concentration [A]. Because of the 1 1 stoichiometry in the balanced chemical reaction and the law of conservation of mass, there is a relationship between [A] and [B] at anytime ... 

In any chemical reaction, the total amount of matter in the reactants is equal to the total amount of matter in the products. Thus, the total mass of all the reactants must be equal to the total mass of all the products. This is known as the law of conservation of mass, which states that there is no change in the total mass of the substances reacting in a balanced chemical reaction. Thus, no material is lost or gained as original substances are changed to new substances. 

In this section we consider a fundamentally important question How much mass of a given reactant is required to produce a given amount of current Conversely, how much current is required to produce a certain amount of product Clearly, the fundamental relationships should be based on conservation of mass and charge. We cannot produce mass from an electrochemical reaction, only rearrange it, and a given amount of reactant can produce a fixed number of charged species, based on the balanced chemical reaction. Consider 1 mol... 

Gravimetric methods based on precipitation or volatilization reactions require that the analyte, or some other species in the sample, participate in a chemical reaction producing a change in physical state. For example, in direct precipitation gravimetry, a soluble analyte is converted to an insoluble form that precipitates from solution. In some situations, however, the analyte is already present in a form that may be readily separated from its liquid, gas, or solid matrix. When such a separation is possible, the analyte s mass can be directly determined with an appropriate balance. In this section the application of particulate gravimetry is briefly considered. 

Thermochemistry. From an overall heat and mass balance point of view, the main chemical reactions of the blast furnace include oxidation of carbon in the zone in front of the tuyeres (raceway) to give CO plus heat. 

If the T and P of a multiphase system are constant, then the quantities capable of change are the iadividual mole numbers of the various chemical species / ia the various phases p. In the absence of chemical reactions, which is assumed here, the may change only by iaterphase mass transfer, and not (because the system is closed) by the transfer of matter across the boundaries of the system. Hence, for phase equUibrium ia a TT-phase system, equation 212 is subject to a set of material balance constraints ... 

The flow of hydrothermal solutions iato the oceans from hydrothermal vents, ie, springs coming from the sea floor ia areas of active volcanism, and the chemical reactions occurring there by high temperature alteration of basalts ate of significance ia the mass balance of and. Eurthermore,... 

Those based on strictly empirical descriptions Mathematical models based on physical and chemical laws (e.g., mass and energy balances, thermodynamics, chemical reaction kinefics) are frequently employed in optimization apphcations. These models are conceptually attractive because a gener model for any system size can be developed before the system is constructed. On the other hand, an empirical model can be devised that simply correlates input-output data without any physiochemical analysis of the process. For... 

An industrial chemical reacdor is a complex device in which heat transfer, mass transfer, diffusion, and friction may occur along with chemical reaction, and it must be safe and controllable. In large vessels, questions of mixing of reactants, flow distribution, residence time distribution, and efficient utilization of the surface of porous catalysts also arise. A particular process can be dominated by one of these factors or by several of them for example, a reactor may on occasion be predominantly a heat exchanger or a mass-transfer device. A successful commercial unit is an economic balance of all these factors. 

To isolate a system for study, the system is separated from the surroundings by a boundary or envelope that may either be real (e.g., a reactor vessel) or imaginary. Mass crossing the boundaiy and entering the system is part of the mass-in term. The equation may be used for any compound whose quantity does not change by chemical reaction or for any chemical element, regardless of whether it has participated in a chemical reaction. Furthermore, it may be written for one piece of equipment, several pieces of equipment, or around an entire process (i.e., a total material balance). 

In situations where no chemical reaction is involved, the balances are based on the masses of the individual components appearing in more than one incoming or outgoing stream. Components that appear in only one incoming stream and one... 

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