# How About Booger Problems in Reaction Stoichiometry

• David Cameron
In summary, I have been teaching introductory general chemistry to engineering majors for over 30 years and have developed a special tool called the "arrow diagram method" for solving difficult problems in reaction stoichiometry. This method is described at www.jimetherdrift2013.net/arrowdiagram.html and is very helpful in solving problems like the one given. The arrow diagram is similar to the conventional ICE table method but uses arrows to represent molar changes for reactants and products. The key to solving these types of problems is logic rather than calculations using the Ideal Gas Law. The value of X(actual) calculated from a measured value is also useful for other calculations such as heat evolved in an exothermic reaction.
David Cameron
TL;DR Summary
The more difficult type of problem, the "Booger problem," is best at exercising logical thinking by the student in solving the problem.
I have taught introductory general chemistry to engineering majors for over 30 years. Upon one occasion, a student told me "I sort of like the homework ... except the booger problems that I can't do." But it is exactly those problems, the more difficult type of problems, that give the student the best problem solving exercise to prepare for quizzes and tests. I have developed a special tool for working out booger problems in reaction stoichiometry. I call this tool the "arrow diagram method." The method is described at www.jimetherdrift2013.net/arrowdiagram.html. The method is very helpful in solving "booger problems" like the following:

NH3 (g) + 5 O2(g) = 4 NO (g) + H2O (l)

When 42 grams of ammonia are reacted with 60 grams of oxygen in a closed container, the final mixture of gases in the container is 42.0 % NO(g) by mass. What is the percent yield of the reaction? ( = 69.1 %)

The arrow diagram solution to this problem, and a couple of similar problems, are posted at www.jimetherdrift2013.net/arrowdiagram.html.

So how does this differ from the conventional ICE table method?

The arrow diagram is very much like the conventional ICE Table. Sometimes, however, the ICE Table uses "mole ratio" to express moles formed or moles used, and the arrow diagram never uses anything like the "mole ratio." The arrow diagram is a little more "dramatic" with the reaction as a PROCESS, using arrows to represent molar changes for reactants and products. Students are most surprised when a reaction has to proceed in the reverse direction to establish equilibrium, so the arrows go down on the right side of the reaction, and up on the left side.

I think in physics we have good reasons to introduce concepts like "mass m", "pressure P", "volume V" and "amount of substance n" and to distinguish them clearly from their units. Hence my question: why do you start out with an equation for P but then instead of n, use "moles of xy"?

I hope this will answer your question. With no temperature or container volume given in the initial problem, there is no way to do calculations with the Ideal Gas Law. Logic, not PV = nRT, is the key to solving this kind of problem. One of the key ideas in solving this problem is that chemical reactions never change TOTAL grams. So with three gases and one liquid in the container at equilibrium, the total grams of gas must be 102 minus the grams of liquid water formed, and 42% of these grams of gas must be grams of NO (g) formed by the reaction. With unit conversion factors in place

(4X mole NO formed)(30 g NO/1 mole NO) = 0.42 (102 grams - (6Xmole H2O formed (18 g H2O/1 mole H2O)))

Solving this equation gives X(actual) = 0.2591. Moles of NO (g) or of H2O (l) actually formed can then be calculated using the value of X(actual) and the percent yield can be calculated as the ratio of actual moles
NO (g) formed over theoretical yield in moles of NO (g) (1.0364/1.500) or actual moles of H2O (l) formed over theoretical yield of H2O (l) in moles (1.5546/2.250) = 69.1%

A complete solution using the "arrow diagram" is posted at www.jimetherdrift2013.net/arrowdiagram.html

So what you call ##x## seems to be what is usually called the "extent of reaction" ##\xi=(n_i-n_i^0)/\nu_i##?

Yes, X(actual), calculated from a measurement given in the problem, IS the extent of reaction. The value of
X(actual) is useful for many things ... such as to calculate actual amount of heat evolved by an exothermic reaction. Students learn reasonably well to set up a logical equation for the calculation of X(actual) from a measured value (like gas pressure or volume of gas), then use the value of X(actual) to answer the question asked in the problem.

## 1. What is reaction stoichiometry?

Reaction stoichiometry is the study of the quantitative relationships between reactants and products in a chemical reaction. It involves using the balanced chemical equation to determine the amount of each substance involved in the reaction.

## 2. How does booger affect reaction stoichiometry?

Booger does not directly affect reaction stoichiometry. However, if a person's hands are dirty or contaminated with boogers, it could potentially introduce impurities into the reaction and affect the overall yield.

## 3. Can booger be used as a reactant in a chemical reaction?

No, booger cannot be used as a reactant in a chemical reaction. Booger is primarily composed of mucus, which is a mixture of water, salts, and proteins. These components do not have the necessary chemical properties to participate in a reaction.

## 4. How can we prevent booger problems in reaction stoichiometry?

To prevent booger problems in reaction stoichiometry, it is important to maintain proper hygiene and cleanliness in the laboratory. This includes washing hands before handling chemicals and using proper techniques to avoid contamination.

## 5. Are there any safety concerns related to booger in reaction stoichiometry?

While booger itself may not pose any significant safety concerns, the potential for contamination and introduction of impurities in the reaction could affect the outcome of the experiment. It is important to follow proper safety protocols and maintain a clean working environment to avoid any potential hazards.

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