Chemical equations precipitation calculations

Tables of amounts are useful in stoichiometry calculations for precipitation reactions. For example, a precipitate of Fe (OH) forms when 50.0 mL of 1.50 M NaOH is mixed with 35.0 mL of 1.00 M FeCl3 solution. We need a balanced chemical equation and amounts in moles to calculate how much precipitate forms. The balanced chemical equation is the net reaction for formation of Fe (OH)3 Fe (ag) + 3 OH (a g) Fe (OH)3 (. )...

The equations used to calculate permeability coefficients depend on the design of the in vitro assay to measure the transport of molecules across membrane barriers. It is important to take into account factors such as pH conditions (e.g., pH gradients), buffer capacity, acceptor sink conditions (physical or chemical), any precipitate of the solute in the donor well, presence of cosolvent in the donor compartment, geometry of the compartments, stirring speeds, filter thickness, porosity, pore size, and tortuosity. 

Recall that stoichiometry involves calculating the amounts of reactants and products in chemical reactions. If you know the atoms or ions in a formula or a reaction, you can use stoichiometry to determine the amounts of these atoms or ions that react. Solving stoichiometry problems in solution chemistry involves the same strategies you learned in Unit 2. Calculations involving solutions sometimes require a few additional steps, however. For example, if a precipitate forms, the net ionic equation may be easier to use than the chemical equation. Also, some problems may require you to calculate the amount of a reactant, given the volume and concentration of the solution. 

Write a balanced chemical equation for the reaction. Find the amount (in mol) of each reactant, using its volume and concentration. Identify the limiting reactant. Determine the amount (in mol) of mercury(II) sulfide that forms. Calculate the mass of mercury(II) sulfide that precipitates. 

A 25.0-mL sample of 0.050 M bariinn nitrate solution was mixed with 25.0 mL of 0.050 M sodiinn sulfate solution labeled with radioactive sulfur-35. The activity of the initial sodium sulfate solution was 1.22 X 10 Bq/mL. After the resultant precipitate was removed by filtration, the remaining filtrate was found to have an activity of 250 Bq/mL. (a) Write a balanced chemical equation for the reaction that occurred, (b) Calculate the K p for the precipitate under the conditions of the experiment. 

As we discussed in Chapter 7, many chemical reactions take place in aqueous solutions. Precipitation reactions, neutralization reactions, and gas evolution reactions, for example, all occur in aqueous solutions. Chapter 8 describes how we use the coefficients in chemical equations as conversion factors between moles of reactants and moles of products in stoichiometric calculations. These conversion factors are often used to determine, for example, the amount of product obtained in a chemical reaction based on a given amount of reactant or the amount of one reactant needed to completely react with a given amount of another reactant. The general solution map for these kinds of calculations is ... 

Fig. 9-8 Histogram of dissolved solids of samples from the Orinoco and Amazon River basins and corresponding denudation rates for morpho-tectonic regions in the humid tropics of South America (Stal-lard, 1985). The approximate denudation scale is calculated as the product of dissolved solids concentrations, mean armual runoff (1 m/yr), and a correction factor to account for large ratios of suspended load in rivers that drain mountain belts and for the greater than average annual precipitation in the lowlands close to the equator. The correction factor was treated as a linear function of dissolved solids and ranged from 2 for the most dilute rivers (dissolved solids less than lOmg/L) to 4 for the most concentrated rivers (dissolved solids more than 1000 mg/L). Bedrock density is assumed to be 2.65 g/cm. (Reproduced with permission from R. F. Stallard (1988). Weathering and erosion in the humid tropics. In A. Lerman and M. Meybeck, Physical and Chemical Weathering in Geochemical Cycles," pp. 225-246, Kluwer Academic Publishers, Dordrecht, The Netherlands.)...

Equation 1.6 shows the precipitation of calcium carbonate, the quantity being calculated from the total calcium and dissolved calcium ions. For the sake of simplicity, it is considered as mol/dm3 units however, in reality, it is a separate solid phase. The chemical species of hydrocarbonate as a function of pH are shown in Figure 1.2. 

Speleothem precipitation rates from thin water films open to the cave atmosphere are controlled by three processes (Baker and Smart, 1995 Baker et al., 1998) 1) chemical reactions at the calcite-solution interface as described by the rate equations of Plummer et al. (1978) through which precipitation rates can be calculated when the concentrations of reactants are known 2) mass transport of reactants through the solution towards or away from the speleothem surface and 3) the rate-limiting reaction H" + HCO = H2O + CO2, through which CO2 is released into the cave atmosphere. Buhmann and Dreybrodt (1985a,b) have solved the transport equations taking into consideration these three mechanisms in order to obtain precipitation rates. For speleothems, Eq.3 can approximate these processes within 10% ... 

To see how molarity can be used in equation stoichiometry problems, let s take a look at the thought process for calculating the number of milliliters of 1.00 M AgN03 necessary to precipitate the phosphate from 25.00 mL of0.500 M Na3P04. The problem asks us to convert from amount of one substance in a chemical reaction to amount of another substance in the reaction, so we know it is an equation stoichiometry problem. The core of our setup will be the conversion factor for changing moles of sodium phosphate to moles of silver nitrate. To construct it, we need to know the molar ratio of AgN03 to Na3P04, which comes from the balanced equation for the reaction. 

As shown in the lower pathway in f-igure 32-8. a destructive method requires that the analyte be separated from the other components of the sample prior to counting. If a chemical separation method is used, this technique is called radiochemical neutron activation. In this case a known amount of the irradiated sample is dissolved and the analyte separated by precipitation, extraction, ion exchange, or chromatography. The isolated material or a known fraction thereof is then counted for its gamma — or beta — activity. As in the nondestructive method, standards may be irradiated simultaneously and treated in an identical way. Equation. 32-21 is then used to calculate the results of the analysis. 

Figure2 Ohnishi et al. (1985) and Chijimatsu et al. (2000)) and reactive-mass transport model (inside the box named Chemical in Figure 2). This is a system of governing equations composed of Equations (l)-(9), which couple heat flow, fluid flow, deformation, mass transport and geochemical reaction in terms of following primary variables temperature T, pressure head y/, displacement u total dissolved concentration of the n master species C< > and total dissolved and precipitated concentration of the n" master species T,. Here we set master species as the linear independent basis for geochemical reactions, and speciation in solution and dissolution/precipitation of minerals are calculated by a series of governing equations for geochemical reaction. Now we adopt equilibrium model for geochemical reaction (Parkhurst et al. (1980)), mainly because of reliability and abundance of thermodynamic data for geochemical reaction.

The data are then plotted as log [>>]M versus Vg, as shown In Figure 2. When the test sample is examined in the same column, the product [ i]M can be read directly from the calibration curve. For calculation of the molecular weight, either of two approaches me(y be followed. If the project is of limited scope, one can determine the intrinsic viscosity of the sample, and calculate M from the product [ ]H obtained directly from the universal calibration curve. For projects with a broader scope, it would be desirable to fractionate a preparation with a broad distribution of molecular weights into fractions with narrow distributions by either preparative SEC or established chemical methods (e.g. selective precipitation with organic solvents). The molecular weights and intrinsic viscosities of these samples would then be determined experimentally, followed by the calculation of the Mark-Houwink constants. Finally, the molecular weight of any sample can be calculated from the [>i]M value read from the curve, by the equation [ i]M =... 

The reaction term ajt includes the sum of the main and side electrochemical reactions and also chemical reactions, as indicated in Equations 25 and 30. Possible chemical reactions of interest in hthium batteries include salt precipitation and homogeneous electrolyte decomposition. Once the rate of the side reaction is added to the model, it can be used to calculate various possible effects of the side reaction in addition to consumption of current. For example, one could calculate the change in porosity due to precipitation of products of the side reaction [19]. Precipitation of solid species might also affect the surface area of active material available for reaction [50]. 

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