Chapter 10

Chemical Calculations and Chemical Equations

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lthough Section 6.7 was full of questions that began with, “How much…?” we are not done with such questions yet. In Section 6.7, our questions focused on chemical formulas. For example, we answered such questions as, “How much of the element vanadium can be obtained from 2.3 metric tons of the compound V2O5?” The chemical formula V2O5 told us that there are two moles of vanadium, V, in each mole of V2O5. We used this molar ratio to convert from moles of V2O5 to moles of vanadium.

In this chapter, we encounter questions that focus instead on chemical reactions. These questions ask us to convert from amount of one substance in a given chemical reaction to amount of another substance participating in the same reaction. For example, a business manager, budgeting for the production of silicon-based computer chips, wants to know how much silicon can be produced from 16 kg of carbon and 32 kg of silica, SiO2, in the reaction

A safety engineer in a uranium processing plant, wants to know how much water needs to be added to 25 pounds of uranium hexafluoride to maximize the synthesis of UO2F2 by the reaction

UF6 + 2H2O → UO2F2 + 4HF

A chemistry student working in the lab might be asked to calculate how much 1-bromo-2-methylpropane, C4H9Br, could be made from 6.034 g of 2-methyl-2-propanol, C4H9OH, in the reaction

3C4H9OH + PBr3 → 3C4H9Br + H3PO3

In these calculations, we will be generating conversion factors from the coefficients in the balanced chemical equation.

10.1 Equation Stoichiometry

10.2 Real-World Applications of Equation Stoichiometry

10.3 Molarity and Equation Stoichiometry

How much product can be made from the given reactants?