Chemical amount

Organophosphoms compounds, primarily phosphonic acids, are used as sequestrants, scale inhibitors, deflocculants, or ion-control agents in oil wells, cooling-tower waters, and boiler-feed waters. Organophosphates are also used as plasticizers and flame retardants in plastics and elastomers, which accounted for 22% of PCl consumed. Phosphites, in conjunction with Hquid mixed metals, such as calcium—zinc and barium—cadmium heat stabilizers, function as antioxidants and stabilizer adjutants. In 1992, such phosphoms-based chemicals amounted to slightly more than 6% of all such plastic additives and represented 8500 t of phosphoms. Because PVC production is expected to increase, the use of phosphoms additive should increase 3% aimually through 1999. 

Just as 1 g and 1 m are units for physical properties, so too is the unit 1 mol. The mole is the unit for the physical property formally called the amount of substance, n. However, that name has found little favor among chemists, who colloquially refer to n as the number of moles. A compromise, which is gaining acceptance, is to refer to n as the chemical amount or simply amount of entities present in a sample. Thus, 1.0000 mol of hydrogen atoms... 

X 1023 hydrogen atoms), which is written 1.0000 mol H, is the chemical amount of hydrogen atoms in the sample. Take the advice of your instructor on whether to use the formal term. Like any SI unit, the mole can be used with prefixes. For example, 1 mmol = 10 3 mol and 1 pmol = 10 6 mol. Chemists encounter such small quantities when dealing with rare or expensive natural products and pharmaceuticals. 

The number of objects per mole, 6.0221 X 1023 mol-1, is called Avogadro s constant, NA, in honor of the nineteenth-century Italian scientist Amedeo Avo-gadro (Fig. E.3), who helped to establish the existence of atoms. Avogadro s constant is used to convert between the chemical amount (the number of moles) and the number of atoms, ions, or molecules in that amount ... 

Suppose a sample of vitamin C is known to contain 1.29 X 1024 hydrogen atoms (as well as other kinds of atoms). What is the chemical amount (in moles) of hydrogen atoms in the sample ... 

Charles, J., 144 Charles s law, 145 chelate, 675 chemical amount, F38 chemical bond, 57 chemical change, F61 chemical engineering, F4 chemical equation, F 62 chemical equilibrium,... 

The mole is a convenient unit for chemical amounts because the mass of most typical laboratoiy samples contains... 

Notice that once again moles are at the center of the scheme. To repeat, calculations of chemical amounts center on the mole. 

As with all calculations of chemical amounts, we must work with moles. Because grams are asked for, we must do a mole-mass conversion this requires the molar mass of the substance, which in turn requires that we know the chemical formula. 

Bush, G.L., A.M.Tassin, H.FridenandD.L.Meyer. (1991) Secretion in yeast. Purification and in vitro translocation of chemical amounts of prepro-alpha-factor. J Biol Chem., 266, 13811-13814. 

Concentration is the chemical amount of substance, , present divided by volume. In the case of gases concentration is used in equilibrium constant expressions, labelled Kc/co (see Appendix). Frequently concentrations are given in units of mol dm-3. Since concentration is also the amount of gas per unit volume, then concentration, c is given by ... 

Equal numbers of atoms and molecules is the same thing as having equal chemical amounts (Frame 1) of atoms and molecules, so that we are looking for the condition where the mole fractions of X and X2 are equal, i.e. ... 

The dependence of entropy change on volume at constant temperature, T, and chemical amount, n can also be shown using the Maxwell relationship. This avoids the consideration of the path-dependent quantities of heat, q, and work, w. Thus ... 

More generally (see later Frame 27), because Gibbs energy is a function of state and because a state is defined by temperature, T, pressure, P, and chemical amounts, ny. 

Chemical Amount of catalyst Pore stmcture Stimng rate... 

Chemical Amounts and Concentrations The amount of a chemical substance is expressed as the number of moles, denoted by n. Energies, entropies. 

Refer to the "The Mole and Chemical Composition" chapter for a discussion of the use of the mole to express chemical amounts. 

Equal chemical amounts of two gases, fluorine and bromine pentafluoride, are mixed. Determine the ratio of the rates of effusion of the two gases through a small opening in their container. 

As the titration curve shows (see Fig. 15.13), the pH increases dramatically in the immediate vicinity of the equivalence point [HjO ] changes by four orders of magnitude between 99.98 mL and 100.02 mL NaOH Any indicator whose color changes between pH = 5.0 and pH = 9.0 therefore signals the endpoint of the titration to an accuracy of 0.02 mL in 100.0 mL, or 0.02%. The titration endpoint, the experimentally measured volume at which the indicator changes color, is then almost identical to the equivalence point, the theoretical volume at which the chemical amount of added base equals that of acid present originally. 

Silver iodide (Agl) is used in place of silver chloride for the fastest photographic film because it is more sensitive to light and can therefore form an image in a very short exposure time. A silver iodide emulsion is prepared by adding 6.60 L of 0.10 M Nal solution to 1.50 L of 0.080 M AgN03 solution at 25°C. Calculate the concentration of silver ion remaining in solution when the mixture comes to equilibrium and its chemical amount relative to the amount present initially. 

A quantity of electricity equal to 9.263 X lO C passes through a galvanic cell that has an Ni(s) anode. Compute the maximum chemical amount, in moles, of Ni (a(j) that can be released into solution. 

This reaction is first order in the chemical amount... 

Compare the relative health risks of contact with a given amount of Ra, which has a half-life of 1622 years and emits 4.78-MeV alpha particles, with contact with the same chemical amount of C, which has a half-life of 5730 years and emits beta particles with energies of up to 0.155 MeV. 

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