Interpreting Chemical Equations

Write a balanced chemical equation. Interpret the equation in terms of moles. 

Challenge For each of the following, balance the chemical equation interpret the equation in terms of particles, moles, and mass and show that the law of conservation of mass is observed. 

Now we come to an important interpretation of a chemical equation. First, we note that the equation for the reaction of sodium with water tells us that... 

The drawings produced by students allow researchers to better conceptualize how some students interpreted a balanced chemical equations. This is especially useful in assessing their understanding of stoichiometric coefficients and the meaning of subscripts of chemical formulae. 

When interpreting the chemical equation for the reaction between aqueous sodium hydroxide and dilute nitric acid, 20% of students appeared to hold the view that Na+ and NO3" ions (submicroscopic and symbolic representations) had reacted in aqueous solution to produce aqueous sodium nitrate. It was not apparent to these students that the net chemical reaction had only involved removal of H+ and OH in aqueous solution to produce molecules of H2O. 

Interpreting Data Write balanced chemical equations for each of the reactions performed. If no reaction was observed write No Reaction. Be sure to show the state for each reactant and product. 

In this chapter, you learned how to balance simple chemical equations by inspection. Then you examined the mass/mole/particle relationships. A mole has 6.022 x 1023 particles (Avogadro s number) and the mass of a substance expressed in grams. We can interpret the coefficients in the balanced chemical equation as a mole relationship as well as a particle one. Using these relationships, we can determine how much reactant is needed and how much product can be formed—the stoichiometry of the reaction. The limiting reactant is the one that is consumed completely it determines the amount of product formed. The percent yield gives an indication of the efficiency of the reaction. Mass data allows us to determine the percentage of each element in a compound and the empirical and molecular formulas. 

After you understand how to interpret chemical symbols, the names of compounds (see Chapter 6), and the symbols in Table 8-1, you can understand almost anything. You re equipped, for example, to decode a chemical equation into an English sentence describing a reaction. Conversely, you can translate an English sentence into the chemical equation it describes. When you re fluent in this language, you regrettably won t be able to talk to the animals you will, however, be able to describe their metabolism in great detail. 

The quantitative interpretation of chemical reactions is the part of chemistry called reaction stoichiometry. Recall from Section H that a stoichiometric coefficient in a chemical equation tells us the relative number of moles of a substance that reacts or is produced. Thus, the stoichiometric coefficients in... 

To interpret a titration, we need the stoichiometric relation from the chemical equation for the reaction. This relation is used to write the mole ratio in the usual way. The only new step is to use the molarities of the solutions to convert between the moles of reactants and the volumes of... 

This entire expression is a thermochemical equation, a chemical equation together with the corresponding enthalpy change. The stoichiometric coefficients in a thermochemical equation are interpreted as the number of moles that react to give the reported change in enthalpy. In this case, the stoichiometric coefficient of CH4 is 1 and that of 02 is 2, so the... 

The enthalpy of reaction, AHr (or reaction enthalpy ), is closely related to the quantity AH that appears in a thermochemical equation, but its units are kilojoules per mole (kj-mol-1) rather than kilojoules. We interpret the per mole to mean per number of moles of each substance as indicated by its stoichiometric coefficient in the chemical equation. For example, the oxidation of methane described by reaction A signifies that 890 kj of heat is released per mole of CFI4 molecules consumed or per... 

A chemical equation represents the relationship of the reactants and products through a numerical relationship expressed by the coefficients associated with the participants. The coefficients can be interpreted as telling us the number of molecules or moles of materials involved but they also represent the volumes of those participants that are gases, assuming a constant temperature and pressure (T and P). An example of these relationships is as follows ... 

You can get the same kind of information from a balanced chemical equation. In Chapter 4, you learned how to classify chemical reactions and balance the chemical equations that describe them. In Chapters 5 and 6, you learned how chemists relate the number of particles in a substance to the amount of the substance in moles and grams. In this section, you will use your knowledge to interpret the information in a chemical equation, in terms of particles, moles, and mass. Try the following Express Lab to explore the molar relationships between products and reactants. 

Explain the different interpretations of the coefficients in a balanced chemical equation. 

In Chapter 7, we learned to interpret chemical formulas in terms of the quantities of the elements involved. In Chapters 8 and 9, we learned to complete and balance chemical equations. This chapter shows how to interpret the quantities of substances involved in a chemical reaction, nsing the balanced chemical eqnation almost as the formnla was nsed in Chapter 7. 

Which of the following statements is a correct interpretation of this balanced chemical equation ... 

SYMBOLS —FORMULAS —CONSERVATION OF MATTER — CHEMICAL EQUATIONS—QUANTITATIVE INTERPRETATION OF EQUATIONS —PROBLEMS BASED ON EQUATIONS — PROBLEMS. 

That chemical equations prove nothing. They simply help us interpret an experiment. They are not a sufficient record of an experiment, and they should never be used unless they have been proved in whole or in part. 

From the above discussions it is evident that equations, accurately evolved and correctly interpreted, reveal the exact proportions by weight in which compounds react in the particular chemical change expressed by the equation. Other facts of fundamental importance are contained in chemical equations, and these will be considered in the proper place. 

The NMR spectra of the ions C4H6D and C4H5D2, prepared from the carbinols as in equations 6 and 7, showed significant isotopic chemical shifts interpreted as showing... 

You should be able to interpret chemical equations, and appreciate that they represent definite quantities of materiab reacting together. You should be familiar with the concepts of exothermic and endothermic reactions. 

Write and interpret a balanced chemical equation for a reaction, and relate conservation of mass to the balanced equation. 

For more practice interpreting chemical equations, go to Supplemental Practice Problems in Appendix A. 

List three ways in which a balanced chemical equation can be interpreted. 

Balanced chemical equations can be interpreted in terms of representative particles (atoms, molecules, formula units), moles, and mass. 

Section 12-1 Interpret the following balanced chemical equation in terms of particles, moles, and mass. 

Interpret balanced chemical equations to calculate the moles of reactants and products involved in each of the reactions... 

A balanced chemical equation may be interpreted on a molecular basis. 

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