Stoichiometry problem-solving strategies

The following Example Problems show mole-to-mole, mole-to-mass, and mass-to-mass stoichiometry problems. The process used to solve these problems is outlined in the Problem-Solving Strategy below. 

The balanced equation states that 6 mol CO2 will be produced from 1 mol C6H12O6. Even though we can readily see that 12 mol CO2 will be formed, let s use the Problem-Solving Strategy for Stoichiometry Problems. 

The balanced equation states that we get 2 mol NH3 for eveiy 3 mol H2 that react. Let s use the Problem-solving Strategy for Stoichiometry Problems. 

Use the Problem-Solving Strategy for Stoichiometry Problems. Solution map ... 

We first use the conversion factor of 1 mol/22.4 L to convert the liters H2 to moles. Then we use our Problem-Solving Strategy for Stoichiometry Problems to find the moles of aluminum produced ... 

Several introductory comments may help you learn how to solve stoichiometry problems. The problem-solving strategy from Section 3.9 is used repeatedly. You will soon see that a series of Per relationships link the Given and Wanted quantities in all problems in this chapter. Therefore, the problems are solved by dimensional analysis. 

Recall that stoichiometry involves calculating the amounts of reactants and products in chemical reactions. If you know the atoms or ions in a formula or a reaction, you can use stoichiometry to determine the amounts of these atoms or ions that react. Solving stoichiometry problems in solution chemistry involves the same strategies you learned in Unit 2. Calculations involving solutions sometimes require a few additional steps, however. For example, if a precipitate forms, the net ionic equation may be easier to use than the chemical equation. Also, some problems may require you to calculate the amount of a reactant, given the volume and concentration of the solution. 

We need to use the strategy for solving stoichiometry problems that we learned in Chapter 3. 

The study of stoichiometry and unit operations concerns itself mainly with the application of steady-state macroscopic balances to chemical process problems. When considering small subsystems of chemical plants, the number of describing relations are small and the development of a computational strategy is not difficult. Usually the relations can be solved directly by partitioning the equations, that is, solving each equation of the equation set for a single unknown variable in a sequential manner. As equation sets become coupled, namely, as each relation involves more of the unknown variables, the probability that an equation set can be partitioned decreases. When an equation set cannot be partitioned, the equations must be solved simultaneously or an iterative scheme devised. 

---