Real-World Applications of Equation Stoichiometry

Let s return to the reaction of solid tetraphosphorus decoxide and water. 

Imagine that it is your joh to design an industrial procedure for running this reaction. Whenever such a procedure is developed, some general questions must he answered, including the following  

To understand some of the issues relating to these questions, let s take a closer look at the reaction of P4O10 and H2O, keeping in mind that we want to react 2.50 X 10 kg P4O10 per day. What if you used a shovel to transfer solid P4O10 into a large container, and then added water with a garden hose Could you expect both of these reactants to react completely When the reaction is finished, would the only substance in the container be phosphoric acid  

To achieve the complete reaction of both reaaants, the coefficients in the balanced equation show us that we would need to add exactly six times as many water molecules as P4O10 molecules. With the precision expected from using a shovel and a hose to add the reactants, this seems unlikely. In fact, it is virtually impossible. The only way we could ever achieve the complete reaction of both reactants is by controlling the addition of reactants with a precision of plus or minus one molecule, and that is impossible (or at least highly improbable). No matter how careful we are to add the reactants in the correct ratio, we will always end up with at least a slight excess of one component compared to the other. 

For some chemical reactions, chemists want to mix reactants in amounts that are as close as possible to the ratio that would lead to the complete reaction of each. This ratio is sometimes called the stoichiometric ratio. For example, in the production of phosphoric acid, the balanced equation shows that six moles of Fi20 react with each mole of P4O10, so for efficiency s sake, or to avoid leaving an excess of one of the reactants contaminating the product, we might want to add a molar ratio of P4O10 to Fi20 as close to the 1 6 stoichiometric ratio as possible. 

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Section 10.2 Real-World Applications of Equation Stoichiometry... 

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