Equation physical states, indicating

Define chemical reaction. Where are the reactants and products shown in an equation for a chemical reaction, and how are the physical states indicated ... 

Each enzyme has a working name, a specific name in relation to the enzyme action and a code of four numbers the first indicates the type of catalysed reaction the second and third, the sub- and sub-subclass of reaction and the fourth indentifies the enzyme [18]. In all relevant studies, it is necessary to state the source of the enzyme, the physical state of drying (lyophilized or air-dried), the purity and the catalytic activity. The main parameter, from an analytical viewpoint is the catalytic activity which is expressed in the enzyme Unit (U) or in katal. One U corresponds to the amount of enzyme that catalyzes the conversion of one micromole of substrate per minute whereas one katal (SI unit) is the amount of enzyme that converts 1 mole of substrate per second. The activity of the enzyme toward a specific reaction is evaluated by the rate of the catalytic reaction using the Michaelis-Menten equation V0 = Vmax[S]/([S] + kM) where V0 is the initial rate of the reaction, defined as the activity Vmax is the maximum rate, [S] the concentration of substrate and KM the Michaelis constant which give the relative enzyme-substrate affinity. 

Additional information may be included when writing a chemical equation. One common practice is to indicate the physical state of substances by use of the subscripts (s), (1), (g), (aq) to indicate solid, liquid, gas, or aqueous (dissolved in water), respectively. Hence, the combustion of carbon to form carbon dioxide would be represented as ... 

Molecular Physics 7, 349(1964) (An Equation of State of Gases at High Temperatures Densities) 15) 4thONRSympDeton (1965) - papers and pages are indicated in the text... 

Equation (56) states that the effect of a thermal gradient on the material transport bears a reciprocal relationship to the effect of a composition gradient upon the thermal transport. Examples of Land L are the coefficient of thermal diffusion (S19) and the coefficient of the Dufour effect (D6). The Onsager reciprocity relationships (Dl, 01, 02) are based upon certain linear approximations that have a firm physical foundation only when close to equilibrium. For this reason it is possible that under circumstances in which unusually high potential gradients are encountered the coupling between mutually related effects may be somewhat more complicated than that indicated by Eq. (56). Hirschfelder (BIO, HI) discussed many aspects of these cross linkings of transport phenomena. 

Just as an increase in solids-not-fat increases milk density, so does the removal of water by processing. If there were no changes in physical state or chemical activity coefficients (e.g., hydration of proteins or insolubilization of salts), the density of the concentrated milk could be calculated from an equation derived by Jenness (1962) and presented in the second edition of this book. Data presented by Mojonnier and Troy (1922) conform to the equation but lack sufficient precision to indicate the small changes associated with some of the changes in physical state. 

This chapter addresses the various phenomena indicated. In addition, the thermodynamic laws governing physical properties of the gas-solid mixture such as density, pressure, internal energy, and specific heat are introduced. The thermodynamic analysis of gas-solid systems requires revisions or modifications of the thermodynamic laws for a pure gas system. In this chapter, the equation of state of the gas-solid mixture is derived and an isentropic change of state is discussed. 

When chemical equations are combined by addition, the standard heats of reaction may also be added to give, the standard heat of the resulting reaction. This is possible because enthalpy is a property, and changes in it are independent of path. In particular, formation equations and standard heats of formation may always be combined to produce any desired equation (not itself a formation equation) and its accompanying standard heat of reaction. Equations written for this purpose often include an indication of the physical state of each reactant and product, i.e., the letter g, l, or s is placed in parentheses after the chemical formula to show whether it is a gas, a liquid, or a solid. This might seem unnecessary since a pure chemical species at a particular temperature and 1 bar or l(atm) can usually exist only in one physical state. However, fictitious states are often assumed as a matter of convenience. 

Write the balanced chemical equation for each double replacement reaction. Be sure to indicate the physical state of all products. 

Explain in your own words and without the use of jargon (a) the three ways of obtaining values of physical properties (b) why some fluids are referred to as incompressible (c) the liquid volume additivity assumption and the species for which it is most likely to be valid (d) the term equation of state (e) what it means to assume ideal gas behavior (f) what it means to say that the specific volume of an ideal gas at standard temperature and pressure is 22.4 L/mol (g) the meaning of partial pressure (h) why volume fraction and mole fraction for ideal gases are identical (i) what the compressibility factor, z, represents, and what its value indicates about the validity of the ideal gas equation of state (j) why certain equations of state are referred to as cubic and (k) the physical meaning of critical temperature and pressure (explain them in terms of what happens when a vapor either below or above its critical temperature is compressed). 

The labeling of r, as a temperature is obviously meant to link the physical properties to human sensory perceptions of hotness levels . Minimally one should ask that the temperature increase monotonically with increasing hotness levels. This requires a quantification scheme that utilizes a convenient equation of state of a suitable material as an indicator of hotness. An enormous multitude of... 

Cubic equations of state have three volume roots, of which two may be complex. Physically meaningful values of V are always real, positive, and greater than constant b. For an isotherm at T > Tc, reference to Fig. 3.12 shows that solutionfor V at ary positive value of P yields only one such root. For the critical isotherm (T = Tc), this is also true, except at the critical pressure, where there are three roots, all equal to Vc- For isotherms at T < Tc, the equation may exhibit one or three real roots, depending on the pressure. Although these roots are real and positive, they are not physically stable states for the portion of an isothenii lying between saturated hquid and saturated vapor (under the "dome"). Only the roots for P = P namely V (liq) and V (vap), are stable states, coimectedby the horizontal portion of the true isotherm. For other pressures (as indicated by the horizontal lines shown on Fig. 3.12 above... 

Write the word equation for the electrolysis of water, and indicate the physical states and condition(s) of the reaction. 

How would you write the skeleton equation that describes the reaction between carbon and sulfur to form carbon disulfide Carbon and sulfur are solids. First, write the chemical formulas for the reactants to the left of an arrow. Then, separate the reactants with a plus sign and indicate their physical states. 

Finally, write the chemical formula for the product, liquid carbon disulfide, to the right of the arrow and indicate its physical state. The result is the skeleton equation for the reaction. 

There are other forms of the Gibbs-Helmholtz equation which are more frequently employed these deal with changes in the free energy, heat content, etc., accompanying an appreciable process. The process may be chemical or physical in nature the only restriction is that it takes place in a closed system, i.e., one of constant mass, which is in equilibrium with the external pressure. For the initial and final states, indicated by the subscripts 1 and 2, respectively, of an isothermal process, equation (25.8) becomes... 

To create the photograph in Figure 4.1, we directed a stream of chlorine gas (GI2) onto solid phosphorus (P4). The mixture burst into flame, and the chemical reaction produced liquid phosphorus trichloride, PGI3. We can depict this using the balanced chemical equation shown opposite, top, which shows the relative amounts of reactants (the substances combined in the reaction) and products (the substances produced). The physical states of the reactants and products are also often indicated in an equation. The symbol (s) indicates a solid, (g) a gas, and (f) a liquid. What the equation does not show are the conditions of the experiment or if any energy (in the form of heat or light) is involved. Lastly, a chemical equation does not tell you if the reaction happens very quickly or if it takes 100 years. 

Figure 2 also shows the density (p) vs temperature phase diagrams of ( () -(, I Ii -N and CO -C Hi -() systems calculated from PR equation of state.The system is single phase outside the envelopes, and separates into two phases in the envelopes. The results in Figure 2 indicate that the differ-rence of p T curves of the two systems is not considerable. The main reasons are that the physical properties of N2 and O2 are similar and their concentrations in the corresponding solutions are low (0.1 mol%). This suggests that N2 can be used to replace O2 for the phase behavior measurements. 

It may also be important to know the physical state of each reactant and product. How can we indicate that the bubbles we see during this reaction are CO2 Symbols in parentheses are put after formulas to indicate the state of the substance. Solids, liquids, gases, and water (aqueous) solutions are indicated by the symbols (s), (1), (g), and (aq). The following equation shows these symbols added to the equation for the reaction of vinegar and baking soda. 

The formula equation can be modified further to show the physical state of each species. If a species is a solid, its formula is followed by (s) if a liquid, by (I) and if a gas, by (g). If a species is dissolved in water, the formula is followed with (aq), indicating it is in an aqueous solution. Going back to our equation, if calcium oxide (a solid), is added to a beaker of water (a liquid), to form a solution of calcium hydroxide, the equation can be modified using the (s), (I), and (aq) attachments to show this. 

For Questions 1 through 5, convert the word equations into balanced formula equations. You do not need to indicate the physical state, (s), (I), (g), or (aq), of the reactants and products. 

In writing thermochemical equations, why is it important to indicate the physical state (that is, gaseous, liquid, solid, or aqueous) of each substance ... 

Write a balanced equation for the preparation of (a) molecular oxygen, (b) ammonia, (c) carbon dioxide, (d) molecular hydrogen, (e) calcium oxide. Indicate the physical state of the reactants and products in each equation. 

Specifying the states of matter. The final equation also indicates the physical state of each substance or whether it is dissolved in water. The abbreviations that are used for these states are solid (5), liquid (Z), gas (g), and aqueous solution (.aq). From the original statement, we know that the Mg wire is solid, the O2 is a gas, and the powdery MgO is also solid. The balanced equation, therefore, is... 

Cases la, lb, and Ic illustrate the difficulties which can arise if one incorporates experimental values of Zc into a cubic equation of state. Excellent representation of the critical isotherm is obtained up to a reduced density of about 0.4, because of the realistic value for Bc built into the equation. Between pT = 0.4 and 1.0, the predicted pressures are a little low, but not unreasonably so. For supercritical densities, however, the quality of the representation deteriorates badly, increasingly so the smaller one makes parameter bc. A large value of bc is not the answer to the problem as indicated by the results of Case Ic, a value of bc = 0.150 improves the predictions up to pT = 1.8, but yields negative pressures for the two highest densities. The reason for this behavior is that for this case the limiting reduced volume (the value of Vr for which Pr —> oo ) is Vr = c/fc = 0.150/0.291 = 0.5155, a number larger than the last two volume entries in the table for Vr < 0.5155, one lands on a physically meaningless branch of the isotherm. 

Besides specifying the compounds involved in the reaction, we often indicate in the equation the physical states of the reactants and products by using the following symbols. 

---