Chemical equations summary

Many conditions are required for a chemical reaction to proceed. Conditions such as heat, light, and pressure must be just right for a reaction to take place. Furthermore, the reaction may proceed very slowly. Some reactions occur in a fraction of a second, while others occur very slowly. Consider the difference in the reaction times of gasoline igniting in a car s cylinder versus the oxidation of iron to form rust. The area of chemistry that deals with how fast reactions occur is known as kinetics (Chapter 12). Finally, not all reactions go to completion. The amount of product produced based on the chemical equation is known as the theoretical yield. The amount actually obtained expressed as a percent of the theoretical is the actual yield. In summary, it s best to think of a chemical equation as an ideal representation of a reaction. The equation provides a general picture of the reaction and enables us to do theoretical calculations, but in reality reactions deviate in many ways from that predicted by the equation. 

In summary, a chemical equation involving defects must balance in three respects ... 

In summary, to determine the products and their physical states in a double displacement reaction, you must first deconstruct the reactants. Then switch the cations, and reconstruct the products using proper chemical formulas. You should then balance the chemical equation. You will be given information to determine which of the products, if any, will form a precipitate. Finally, you can write the physical state—(s) or (aq)— of each product and balance the equation. 

Metallurgy is the study of extracting and purifying metals from their ores. Conduct research to learn how iron is extracted from its ores, how it is purified, and how steel is made. Make a poster showing the steps in these processes, and include a short summary of each step and the chemical equations involved. 

You will notice that the first molecular formula, which represents glucose, is not preceded by a coefficient. When this is the case, we understand there to be only one molecule or formula unit involved in the balanced chemical equation. There is a coefficient of 6 preceding each of the other chemical formulas, indicating the six molecules of each of the other substances are involved in the chemical reaction. In summary, the reaction shows us that one molecule of glucose will react with six molecules of diatomic oxygen, to form six molecules of carbon dioxide and six molecules of water. 

We express all concentrations in moles per liter. The mole ratio from the balanced chemical equation allows us to find the changes in concentrations of the other substances in the reaction. We use the reaction summary to find the equihbrium concentrations to use in the... 

In Examples 18-8 and 18-9 the value of an equilibrium concentration was used to determine the change in concentration. You should become proficient at using a variety of data to determine values that are related via a chemical equation. Let s review what we did in Example 18-9. Only the equilibrium expression, initial concentrations, and the equilibrium concentration of H3O+ were known when we started the reaction summary. The following steps show how we filled in the remaining values in the order indicated by the numbered red arrows. 

We recognize that both NaCH3COO and NaCN are salts of strong bases and weak acids. The anions in such salts hydrolyze to give basic solutions. As we have done before, we first write the appropriate chemical equation and equihbrium constant expression. Then we complete the reaction summary, substimte the algebraic representations of equilibrium concentrations into the equilibrium constant expression, and solve for the unknown concentration(s). 

The most basic summary of the photosynthesis process can be shown with a net chemical equation... 

In reallity the chemical equation (1.4) does not tell us how reactants become products - it is a summary of the overall process. In fact it is molecularity, e.g. the number of species that must collide to produce the reaction which determines the form of a rate equation. Reactions whose rate law can be written from its molecularity are called elementary. The kinetics of the elementary step depends only on the number of reactant molecules in that step. 

Below is a summary of steps that can be followed to balance a chemical equation. Keep in mind that there is a limit to the usefulness of following a set of rules for this procedure. Ultimately, it is a matter of experience and good judgment. In general, the best sequence of steps to take is the following ... 

Figures. Summary of amount-mass-number relationships in a chemical equation. Start at any box (known) and move to any other (unknown) by using the conversion factor on the arrow. As always, convert to amount (mol) first.

Reversing the chemical equation changes the equilibrium constant to its reciprocal. In summary. 

If only the reactivity ratios and reference are given, then, either no experimental data was given or the journal was not available and the Chemical Abstracts summary was the source of the data. If a Y or N (yes or no) appears in the conversion (Conv.) column then the reactivity ratios were recalculated. If a recalculation was performed but the 95% confidence columns (95%) are still left blank, it indicates that only two feed/polymer data pairs were available. In general, if there is a citation (Y or N) in die Conv. column but no reactivity ratios are shown in the reactivity ratio columns, the copolymerization did not follow the copolymerization equation (ionic or penultimate effects were prevalent). In a few cases, the data were too scattered to allow a reactivity ratio calculation. 

EXAMPLE 21-1 Writing Chemical Equations from a Summary Diagram of Reaction Chemistry... 

The reaction summary diagram identifies only some of the substances involved in the various reaction pathways. Writing down an incomplete chemical equation for a reaction can often make it easier to identify other reactants and products that are involved. 

It is important to distinguish between these two uses of identical-appearing chemical shorthand expressions Combustion reactions occur because large numbers of different elementary reactions combine to produce the transformation of fuel and oxidizer to combustion products described in the chemical equation. The whole set of elementary reactions is called the reaction mechanism. In summary, combustion reactions can be described at the molecular level by giving the elementary reactions that comprise the combustion mechanism of the fuel of interest. In Section 8 of Chapter 5 can be found a selection of elementary reactions that one might assemble into a mechanism for the combustion of propane, for example. 

Panagiotopoulos et al. [16] studied only a few ideal LJ mixtures, since their main objective was only to demonstrate the accuracy of the method. Murad et al. [17] have recently studied a wide range of ideal and nonideal LJ mixtures, and compared results obtained for osmotic pressure with the van t Hoff [17a] and other equations. Results for a wide range of other properties such as solvent exchange, chemical potentials and activity coefficients [18] were compared with the van der Waals 1 (vdWl) fluid approximation [19]. The vdWl theory replaces the mixture by one fictitious pure liquid with judiciously chosen potential parameters. It is defined for potentials with only two parameters, see Ref. 19. A summary of their most important conclusions include ... 

In summary, in the limit as x2 —> 0 and xi — 1, /i —>.V /f and f2 —> x2A h..x-It can be shown from the Gibbs-Duhem equation that when the solute obeys Henry s law, the solvent obeys Raoult s law, To prove this, we start with the Gibbs-Duhem equation relating the chemical potentials... 

This expression is called a skeletal equation because it shows the bare bones of the reaction (the identities of the reactants and products) in terms of chemical formulas. A skeletal equation is a qualitative summary of a chemical reaction. 

Mechanism I illustrates an important requirement for reaction mechanisms. Because a mechanism is a summary of events at the molecular level, a mechanism must lead to the correct stoichiometry to be an accurate description of the chemical reaction. The sum of the steps of a mechanism must give the balanced stoichiometric equation for the overall chemical reaction. If it does not, the proposed mechanism must be discarded. In Mechanism I, the net result of two sequential elementary reactions is the observed reaction stoichiometry. 

Data Structures. Inspection of the unit simulation equation (Equation 7) indicates the kinds of input data required by aquatic fate codes. These data can be classified as chemical, environmental, and loading data sets. The chemical data set , which are composed of the chemical reactivity and speciation data, can be developed from laboratory investigations. The environmental data, representing the driving forces that constrain the expression of chemical properties in real systems, can be obtained from site-specific limnological field investigations or as summary data sets developed from literature surveys. Allochthonous chemical loadings can be developed as worst-case estimates, via the outputs of terrestrial models, or, when appropriate, via direct field measurement. 

Results of adsorption experiments for butylate, alachlor, and metolachlor in Keeton soil at 10, 19, and 30°C were plotted using the Freundlich equation. A summary of the coefficients obtained from the Freundlich equation for these experiments is presented in TABLE IV. Excellent correlation using the Freundlich equation over the concentration ranges studied (four orders of magnitude) is indicated by the r values of 0.99. The n exponent from the Freundlich equation indicates the extent of linearity of the adsorption isotherm in the concentration range studied. If n = 1 then adsorption is constant at all concentrations studied (the adsorption isotherm is linear) and K is equivalent to the distribution coefficient between the soil and water (Kd), which is the ratio of the soil concentration (mole/kg) to the solution concentration (mole/L). A value of n > 1 indicates that as the solution concentration increases the sorption sites become saturated, resulting in a disproportionate amount of chemical being dissolved. Since n is nearly equal to 1 in these studies, the adsorption isotherms are nearly linear and the values for Kd (shown in TABLE IV) correspond closely to K. These Kd values were used to calculate heats of adsorption (AH). 

Ionic equations provide useful summaries of the overall changes occurring in a chemical reaction. In an ionic equation, only the species taking part in the reaction are included. 

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