This is frequently seen when pretreating a complex organic wastewater for toxicity reduction.
The following video considers the first part of this: Product formation is discussed elsewhere. It was Richter who coined the term stoichiometry, a tongue-twisting word that baffles students to this day.
Stoichiometry was derived from stoikheion, Greek for "element", and "metron", meaning measure. What Richter discovered was that it was possible to quantify the amount of substances consumed or produced by a chemical reaction.
Richter was working with the following reaction of magnesium oxide neutralizing sulfuric acid. He figured out that there was a definite proportion between the amount of magnesium oxide and the amount of sulfuric acid with which it reacted.
He phrased his conclusion as: If I had grams of sulfuric acid, I would have to use twice as much magnesium oxide, or grams of magnesium oxide to neutralize it. So how do we think about this in modern terms? We now know that magnesium oxide is a molecule consisting of one magnesium atom and one oxygen atom, MgO, and that sulfuric acid is the molecule H2SO4.
We also know that the neutralization reaction produces MgSO4 and water.
One molecule H2SO4 Richter's discovery of specific proportions is a consequence of this one to one reaction. Before moving forward, let's switch to a different reaction that is not one to one: This is the type of question that reaction stoichiometry can help us answer. Let me go back to our original question: I start with my given quantity: Our question is on the macroscopic scale: However, the reaction, which tells us that one molecule of Pb NO3 2 reacts with two molecules of NaI, is expressed on the microscopic scale: The molecular weight will be very useful here, since it allows us to go back and forth between the mass of a substance and the number of molecules of that substance.
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Multiplying by 1 mole of Pb NO3 2 for every I now know the number of molecules of Pb NO3 2 present in The chemical reaction tells me that 2 molecules of NaI are consumed for every molecule of Pb NO3 2 that is consumed. This is captured by the ratio: To get to the macroscopic scale, I again use the molecular weight: I've used the chemical reaction, which tells me that at the molecular scale 2 mol of NaI are consumed for every 1 mol of Pb NO3 2 consumed.
I converted to this to the macroscopic scale to find that 9. This type of macroscopic relationship is the type of macroscopic relation that Richter discovered back in the 's.
Richter was the first person to discover and quantify this type of relationship, and he laid out the basic principles of stoichiometry that we use to this day. This was long before the molecular structure of matter was understood, so his results were all phrased at the macroscopic scale of grams.
Unfortunately, Richter was a bad writer and his papers were hard to read. It took about 5 years before people began to really read his work and be influenced by it. Once it began to be read, it did not take long for some scientists to realize that Richter's definite proportions could be explained by assuming that molecules exist.
They hypothesized that matter consists of molecules and that these molecules react though chemical equations with simple coefficients, such as those seen here in which two molecules of NaI react with one molecule of Pb NO3 2. However, it took another years to fully develop the molecular theory of matter to a point where it was accepted by most scientists.
Richter's discover of stoichiometry was an important first step along the way to developing the modern molecular view of chemistry.SAFETY FIRST - Chemistry experiments should be done in a controlled, carefully supervised environment such as a school lab (laboratory) or learning center lab unless specifically designed to be safe as a home experiment.
Children must be constantly supervised by informed responsible adults educated in lab safety. Never work alone. If you plan on doing any experiments of any kind, pay. Conclusions (which you may contest) As this can be easily achieved in almost any Rietveld program, the Le Bail method caused a marked and radical increase in the .
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