Equation, chemical

The chemical equation for combustion is then written asij/ J... 

In a weak electrolyte (e.g. an aqueous solution of acetic acid) the solute molecules AB are incompletely dissociated into ions and according to the familiar chemical equation... 

The logarithm of the equilibrium constant, K,. for the chemical equation shown in Figure 3-8a for a substituted benzoic acid can be related to the logarithm of the... 

A basic assumption in such additivity schemes is that the interactions between the atoms of a molecule are of a rather short-range nature. This fact can be expressed in a more precise manner The law of additivity can be expressed in a chemical equation [1]. Let us consider the atoms (or groups) X and Y attached to a common skeleton, S, and also the redistribution of these atoms on that skeleton as ejqjressed by Eq. (1). 

In order to obtain an improved yield of the desired product, an excess over the proportion required by the chemical equation of one (or more) of the reactants is often used. In a given preparation, the selection of the reagent to be employed in excess will depend upon a number of factors these include its relative cost and ease of removal after the reaction, and... 

Wnte a balanced chemical equation for the combustion of each of the following compounds... 

We 11 often write chemical equations m the abbreviated form shown here m which reagents especially inorganic ones are not included m the body of the equation but... 

Write chemical equations for the reaction that takes place... 

Wnte a chemical equation for the reaction of 1 butanol with each of the following... 

By carrying out the reaction at —78°C it is possible to fluonnate 2 2 dimethylpropane to yield (CF3)4C Write a balanced chemical equation for this reaction... 

Write a chemical equation showing the preparation of octade... 

Show by writing appropriate chemical equations how each of the following compounds could be converted to 1 hexyne... 

Show by wnting a suitable sequence of chemical equations how to prepare each of the fol lowing compounds from cyclopentene and any necessary organic or inorganic reagents... 

Write chemical equations showing how you could prepare... 

In each of the following pairs of compounds choose which one will react faster with the indicated reagent and wnte a chemical equation for the faster reaction... 

Wnte chemical equations showing all necessary reagents for the preparation of 1 butanol by each of the following methods... 

The rate of a process is expressed by the derivative of a concentration (square brackets) with respect to time, d[ ]/dt. If the concentration of a reaction product is used, this quantity is positive if a reactant is used, it is negative and a minus sign must be included. Also, each derivative d[ ]/dt should be divided by the coefficient of that component in the chemical equation which describes the reaction so that a single rate is described, whichever component in the reaction is used to monitor it. A rate law describes the rate of a reaction as the product of a constant k, called the rate constant, and various concentrations, each raised to specific powers. The power of an individual concentration term in a rate law is called the order with respect to that component, and the sum of the exponents of all concentration terms gives the overall order of the reaction. Thus in the rate law Rate = k[X] [Y], the reaction is first order in X, second order in Y, and third order overall. 

A mechanism is a series of simple reaction steps which, when added together, account for the overall reaction. The rate law for the individual steps of the mechanism may be written by inspection of the mechanistic steps. The coefficients of the reactants in the chemical equation describing the step become the exponents of these concentrations in the rate law for... 

Several other chemical reactions are also widely used for the synthesis of these polymers. This list enumerates some of the possibilities and Table 5.3 illustrates these reactions by schematic chemical equations ... 

Chemical Equations Chemical changes are discussed with the aid of the equations used to treat equiUbrium, ie, the reaction of reactants B, C, and so on, to produce products P, Q, and so forth. 

The essential information implied by the chemical equation is the stoichiometry at the macroscopic level, ie, if a moles of M react, then b moles of B do also p moles of P are formed, etc. No inference should be made about behavior at the microscopic or atomic level, ie, there is no implication thatp molecules of P appear simultaneously. There may or may not be intermediates that appear and disappear in the course of the reaction. 

Results may be reported for any component. The functional form of the rate law and the exponents x,j, w,... are not affected by such an arbitrary choice. The rate constants, however, may change in numerical value. Similarly, the stoichiometric chemical equation may be written in alternative but equivalent forms. This also affects, at most, the numerical value of rate constants. Consequentiy, one must know the chemical equation assumed before using any rate constant. 

Mechanisms. Mechanism is a technical term, referring to a detailed, microscopic description of a chemical transformation. Although it falls far short of a complete dynamical description of a reaction at the atomic level, a mechanism has been the most information available. In particular, a mechanism for a reaction is sufficient to predict the macroscopic rate law of the reaction. This deductive process is vaUd only in one direction, ie, an unlimited number of mechanisms are consistent with any measured rate law. A successful kinetic study, therefore, postulates a mechanism, derives the rate law, and demonstrates that the rate law is sufficient to explain experimental data over some range of conditions. New data may be discovered later that prove inconsistent with the assumed rate law and require that a new mechanism be postulated. Mechanisms state, in particular, what molecules actually react in an elementary step and what products these produce. An overall chemical equation may involve a variety of intermediates, and the mechanism specifies those intermediates. For the overall equation... 

A.mmonium C/j/oride. Work on the distribution of ammonium chloride [12125-02-9] between the vapor andhquid phases (8) suggests that the Ray diagram is sometimes an oversimplification. In most steam systems, there is much more ammonia than any other impurity. In particular, there is more ammonia than hydrogen chloride. The volatiUty of ammonium chloride is therefore expressed by the following chemical equation ... 

Systematic elimination of G and O2 from this set of chemical equations reduces the set to two. Three possible pairs of equations may result, depending on how the combination of equations is effected. Any of the following three equa-... 

Theoretical Oxygen and Air for Combustion The amount of oxidant (oxygen or air) just sufficient to burn the carbon, hydrogen, and sulfur in a fuel to carbon dioxide, water vapor, and sulfur dioxide is the theoretical or stoichiometric oxygen or air requirement. The chemical equation for complete combustion of a fuel is... 

In all of these oxide phases it is possible that departures from the simple stoichiometric composition occur dirough variation of the charges of some of the cationic species. Furthermore, if a cation is raised to a higher oxidation state, by the addition of oxygen to tire lattice, a conesponding number of vacant cation sites must be formed to compensate tire structure. Thus in nickel oxide NiO, which at stoichiomen ic composition has only Ni + cations, oxidation leads to Ni + ion formation to counterbalance the addition of extra oxide ions. At the same time vacant sites must be added to the cation lattice to retain dre NaCl sUmcture. This balanced process can be described by a normal chemical equation thus... 

In liquid metal solutions Z is normally of the order of 10, and so this equation gives values of Ks(a+B) which are close to that predicted by the random solution equation. But if it is assumed that the solute atom, for example oxygen, has a significantly lower co-ordination number of metallic atoms than is found in the bulk of die alloy, dieii Z in the ratio of the activity coefficients of die solutes in the quasi-chemical equation above must be correspondingly decreased to the appropriate value. For example, Jacobs and Alcock (1972) showed that much of the experimental data for oxygen solutions in biiiaty liquid metal alloys could be accounted for by the assumption that die oxygen atom is four co-ordinated in diese solutions. 

Stoichiometric The exact quantity of reactants required to ctrmpletely react according to a particular chemical equation. If... 

---