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Every chemistry paper asks you to work out how many grams of one substance react with a given mass of another. The word for that skill, stoichiometry, was coined by a Prussian mining official who did chemistry in his spare time. This post covers who Jeremias Richter was, what he found, and how his idea looks in a modern worked example.
Who was Jeremias Richter?
According to his entry in the Neue Deutsche Biographie, Jeremias Benjamin Richter was born on 10 March 1762 in Hirschberg, Silesia, and died in Berlin in 1807. He joined the Prussian engineering corps in 1778, then studied philosophy and mathematics at Königsberg from 1785 to 1789, attending lectures by Immanuel Kant. His doctoral thesis of 1789 was titled "De usu matheseos in chymia", on the use of mathematics in chemistry.
He never held a university post in chemistry. He worked as a surveyor, then as an assayer for the Silesian mining office in Breslau, and from 1800 as an official of the mining administration in Berlin, where he also worked at the royal porcelain factory. The same article says his chemistry was done entirely on the side and that his practical skills were self-taught.
What did Richter discover?
Richter mixed solutions of two neutral salts and noticed that when they exchanged partners, the two new salts were also neutral. The NDB article explains what he concluded: there must be fixed proportions between the parts of a neutral salt. He then measured how much of each base neutralised a given amount of each acid and drew up tables of these amounts.
His three-part book, "Anfangsgründe der Stöchyometrie" (1792 to 1794), gave the subject its name. The older Allgemeine Deutsche Biographie entry on the same page explains that the word comes from the Greek for element and for measuring. The NCERT Class 11 chapter Some Basic Concepts of Chemistry gives the same root: stoicheion (element) and metron (measure).
Why was he ignored for so long?
The NDB lists several reasons. He wrote in an obscure style. He still used parts of the old phlogiston theory when most chemists had moved to Lavoisier's ideas. He also tried to force his numbers into neat patterns, claiming that the neutralising amounts of bases formed an arithmetic series and those of acids a geometric one, which turned out to be wrong. Berzelius even credited the key discovery to an earlier chemist, Carl Wenzel. Only in 1841 did Germain Henri Hess, of Hess's law, point out Richter's priority in print.
Worked example: Richter's idea in modern units
Richter's tables listed amounts of acids that each neutralise the same amount of a base, which later chemists called equivalents. We now express this with moles. Using the IUPAC abridged atomic weights (H 1.0080, O 15.999, Na 22.990, S 32.06, Cl 35.45):
Molar masses. NaOH = 22.990 + 15.999 + 1.0080 = 39.997 g/mol. HCl = 1.0080 + 35.45 = 36.458 g/mol. H2SO4 = 2(1.0080) + 32.06 + 4(15.999) = 98.072 g/mol.
Equations. NaOH + HCl → NaCl + H2O, and 2NaOH + H2SO4 → Na2SO4 + 2H2O.
Equivalent masses. 39.997 g of NaOH is neutralised by 36.458 g of HCl, or by 98.072 / 2 = 49.036 g of H2SO4. So 36.458 g of HCl and 49.036 g of H2SO4 do the same job. That is the kind of table Richter built.
A question. What mass of H2SO4 neutralises 10.0 g of NaOH? Moles of NaOH = 10.0 / 39.997 = 0.2500. Moles of H2SO4 = 0.2500 / 2 = 0.1250. Mass = 0.1250 × 98.072 = 12.26 g.
Which mistakes does this help you avoid?
Ignoring the 2 in the equation. Using a 1 : 1 ratio for NaOH and H2SO4 gives 24.5 g, double the right answer.
Using rounded or wrong molar masses. Write each molar mass out once, with its sum, before you use it.
Mixing grams and moles. Convert to moles, use the ratio from the equation, then convert back.
The JEE (Main) 2026 syllabus lists "Chemical equations and stoichiometry" in its first chemistry unit, so this method is tested directly. Check the syllabus for your own exam year. For the next step, read our guide to limiting reagent problems and the post on Joseph Proust and definite proportions, who worked on the same question from another direction.
What can a student take from Richter's way of working?
Measure, then tabulate. His tables of neutralising amounts were the useful part of his work, and they still make sense today.
Bring maths into the lab. His thesis argued that chemistry should be measured and calculated, an idea that now runs through every numerical you solve.
Write clearly. Good results in an unreadable style were ignored for decades.
When a mole calculation goes wrong and you cannot see where, the Fermi Problem Library has worked problems with a step-by-step solver that explains the reasoning rather than printing an answer.
Try it now: work out the mass of HCl that neutralises 5.6 g of KOH, writing each molar mass in full first.
