chemistry

Karl Friedrich Mohr

Karl Friedrich Mohr is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Karl Friedrich Mohr rather than just read about it. In short: Karl Friedrich Mohr (November 4, 1806 – September 28, 1879) was a German chemist famous for his early statement of the principle of the conservation of energy. Ammonium iron(II) sulfate, (NH4)2Fe(SO4)2.6H2O, is named Mohr's salt after him.

Key takeaways

Karl Friedrich Mohr belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Karl Friedrich Mohr to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Karl Friedrich Mohr from memory before moving on to harder problems.

Reference excerpt

Karl Friedrich Mohr (November 4, 1806 – September 28, 1879) was a German chemist famous for his early statement of the principle of the conservation of energy. Ammonium iron(II) sulfate, (NH4)2Fe(SO4)2.6H2O, is named Mohr's salt after him.

Life Mohr was born in 1806 into the family of a prosperous druggist in Koblenz. The young Mohr received much of his early education at home, a great part of it in his father's laboratory. This experience may be responsible for much of the skill Mohr later showed in devising instruments and methods of chemical analysis. At the age of twenty-one he began to study chemistry under Leopold Gmelin, and, after five years in Heidelberg, Berlin and Bonn, he returned with the degree of PhD to join his father's establishment. Mohr's father died during 1840 at which time Mohr assumed control of the family business. He retired from it for a life of scientific leisure in 1857, but at the age of fifty-seven some serious financial losses caused him to become a privatdozent in Bonn. In 1859, Mohr was one of the 56 founding members of the Freies Deutsches Hochstift (Free German Foundation). In 1867 he was appointed, by the direct influence of the government, extraordinary professor of pharmacy.

Work Mohr was the leading scientific chemist of his time in Germany, and the inventor of many improvements in analytical methodology. He invented an improved burette which had a tip at the bottom and a clamp (a 'Mohr's clip'), which made it much easier to use than its predecessors, which were more similar to a graduated cylinder. His methods of volumetric analysis were expounded in his Lehrbuch der chemisch-analytischen Titrir-methode (1855) (Instructional Book of Titration Methods in Analytical Chemistry), which won special commendation from Liebig and ran to many editions. His Geschichte der Erde, eine Geologie auf neuer Grundlage (1866) (History of the Earth, a Geology on a New Basis), was also widely circulated. In a paper Über die Natur der Wärme (1837), Mohr gave one of the earliest general statements of the doctrine of the conservation of energy:

besides the 54 known chemical elements there is in the physical world one agent only, and this is called Kraft (energy). It may appear, according to circumstances, as motion, chemical affinity, cohesion, electricity, light and magnetism; and from any one of these forms it can be transformed into any of the others.

Selected writings

Lehrbuch der pharmaceutischen Technik. Braunschweig: Friedrich Bieweg, 1847. 1866 edition digitized [2] This was the first textbook of pharmacy. It was translated and adapted to English practice by Theophilus Redwood. The US version was translated and adapted by William Procter, Jr. Commentar zur Preußischen Pharmacopoe nebst Übersetzung des Textes : nach der 6. Aufl. der Pharmacopoea Borussica bearbeitet ; für Apotheker, Aerzte und Medicinal-Beamte . Band 1 . Vieweg, Braunschweig 1848 Digital edition by the University and State Library Düsseldorf Commentar zur Preußischen Pharmacopoe nebst Übersetzung des Textes : nach der 6. Aufl. der Pharmacopoea Borussica bearbeitet ; für Apotheker, Aerzte und Medicinal-Beamte . Band 2 . Vieweg, Braunschweig 1849 Digital edition by the University and State Library Düsseldorf Commentar zur preussischen Pharmacopoe nebst Übersetzung des Textes : nach der sechsten Auflage der Pharmacopoea Borussica ; für Apotheker, Ärzte und Medicinal-Beamte Vol.1-2 . Vieweg, Braunschweig 2nd edition 1854 Digital edition by the University and State Library Düsseldorf Lehrbuch der chemisch-analytischen Titriermethode : für Chemiker, Ärzte u. Pharmaceuten, Berg- und Hüttenmänner, Fabrikanten, Agronomen, Metallurgen, Münzbeamte etc. ; nach eigenen Versuchen und systematisch dargestellt . Vieweg, Braunschweig 3. Aufl. 1870 Digital edition by the University and State Library Düsseldorf Mohr, Friedrich (1877). Lehrbuch der chemisch-analytischen Titrirmethode: Nach eigenen versuchen. Braunschweig: Freidrich Vieweg und Sohn. p. 80. Lehrbuch der chemisch-analytischen Titrir-methode. - Based on Mohr's work

Illustrations

Worked examples

Example 1 — a first encounter with Karl Friedrich Mohr

Start with the simplest possible case. Write down what Karl Friedrich Mohr claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Karl Friedrich Mohr before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Karl Friedrich Mohr ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Karl Friedrich Mohr

In research: Karl Friedrich Mohr appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Karl Friedrich Mohr in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Karl Friedrich Mohr is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1806 births, 1879 deaths, 19th-century German chemists, so understanding it makes those chapters shorter.
In everyday life: Look for Karl Friedrich Mohr outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Karl Friedrich Mohr in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Karl Friedrich Mohr means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Karl Friedrich Mohr out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Karl Friedrich Mohr in simple terms?

Why does Karl Friedrich Mohr matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Karl Friedrich Mohr?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Karl Friedrich Mohr.