Chemical arithmetic

Stoichiometry Chemical Arithmetic 3.12 Determining Empirical Formulas Elemental Analysis... 

Clark s Methods in Microscopy. Detailed descriptions of successful methods. 1.60. Coit s Chemical Arithmetic. With a short system of analysis. 50 cents. Coleman s Elements of Physics. For secondary schools. 1.25. 

One of the most important areas of chemical arithmetic is based on balanced chemical equations. Chemists call this area of endeavor stoichiometry (stoy-key-om -ah-tree), which concerns the quantitative relationships between the reactants and products in chemical reactions. Stoichiometric calculations can be used to determine the amount of one reactant needed to completely react with another, or to determine the amount of reactant needed to produce a desired amount of product. The key to understanding how this is done is found in the way balanced chemical equations can be interpreted. So that is the place to begin learning the arithmetic of balanced chemical equations. 

Figuring out how much sodium azide is needed to produce enough nitrogen to properly inflate the bag is an example of a practical application of the chemical arithmetic that we are learning in this chapter.

In this chapter we define the mole, the fimdamental unit of measure of chemical arithmetic, learn to write and balance chemical equations, and use these tools to perform calculations of chemical quantities. 

The mole is the basis of our calculations. However, moles are generally measured in grams (or kilograms). A facility for interconversion of moles and grams is fim-damental to chemical arithmetic (see Figure 5.2). These calculations are reviewed in Example 5.14. 

In our discussion of the chemical arithmetic of reactions in Chapter 5, we saw that the chemical equation represents the relative number of moles of reactants producing products. When chemical reactions occur in solution, it is most useful to represent their concentrations on a molar basis. 

Solution The formula C7H5N, implies that the compound is multi-unsaturated. This is seen by the following chemical arithmetic. 

Chemical stoichiometry is the area of study that considers the quantities of materials in chemical formulas and equations. Quite simply, it is chemical arithmetic. The word itself is derived from stoicheion, the Greek word for element and metron, the Greek word for measure. When based on chemical formulas, stoichiometry is used to convert between mass and moles, to calculate the number of atoms, to calculate percent composition, and to interpret the mole ratios expressed in a chemical formula. Most topics in chemical arithmetic depend on the interpretation of balanced chemical equations. Mass/mole conversions, calculation of limiting reagent and percent yield, and various relationships among reactants and products are commonly included in this topic area. 

Thinking it Through Often chemical arithmetic is based not on a mass measurement, but on a volume measurement. The molarity of a solution expresses the number of moles of solute in a liter of solution. It is straightforward in this case to predict the volume of SO iaq) that will be required. The SO (aq) is halfes concentrated as the Ff (aq> solution, but only half Has number of moles are required according to the balanced equation. Therefore, 24.0 mL of the SO (aq) will be required for the titration to be completed. This is choice (B). 

Note that each quantity includes a unit refer to Appendix I for a review of dimensional numbers. The rigorous use of dimensional units is particularly important in chemical arithmetic. 

Chemical arithmetic. Find the mass of CI2 obtained by decomposition of 35 g of FeCla, 2 FeCWZ) 2FeCl,(c) + Cl3(g). 

Chemical arithmetic. How many water molecules are produced when 100 liters of Nj04 at standard conditions is consumed See Problem 7. 

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