Today is Mole Day, an unofficial holiday celebrated among chemists, chemistry students and chemistry enthusiasts on October 23, between 6:02 AM and 6:02 PM. No, it does not celebrate pesky little furry mammals who make hills that some people make into mountains. The mole is the unit of measurement in the International System of Units (SI) for the amount of a substance. You might have a tough time for a few seconds if your eyes glaze over when the subject of mathematics comes up. I promise to be quick.
The mole is widely used in chemistry as a convenient way to express relative amounts of reactants and products of chemical reactions. For example, the chemical equation 2 H2 + O2 → 2 H2O implies that 2 mol of dihydrogen (H2) and 1 mol of dioxygen (O2) react to form 2 mol of water (H2O). The mole may also be used to express the number of atoms, ions, or other elementary entities in a given sample of any substance. The concentration of a solution is commonly expressed by its molarity, defined as the number of moles of the dissolved substance per liter of solution. This takes me back to my days of quantitative analysis in chemistry lab in grammar school. I used to be all right with the experiments, but I always managed to get tripped up on the mathematics at the end. I knew my chemistry backwards, forwards, and inside out – yet I still managed to make a simple error in calculation on the quantitative analysis in the final lab exam for ‘O’- level and fretted for a month until the results were published. Crisis over. Even with one simple error in multiplication on one tiny part of the whole exam I still got the highest mark. Phew !!
The mole is based on Avogadro’s constant, which is approximately 6.02 × 1023 (actually more like 6.02214085774×1023) and which is the number of particles (usually atoms or molecules) in one mole of substance. In the US writing style today’s date is 10/23, so at 6:02 (the time I woke this morning as it happens – late for me), we can say that we have approximated Avogadro’s constant (6:02 10/23) in the same way that 10/6 (October 6 in US, 10 June in Britain) is Mad Hatter’s Day, or 22/7 (22 July in Britain) is Pi Approximation Day. Semi-officially, Mole Day runs from 6:02 am to 6:02 pm.
You can convert moles to grams by using the common isotope for carbon which is carbon-12. I mole of carbon-12 weighs 1 gram (which is also one way to define a gram – that is, 6.02 × 1023 atoms of carbon-12 = 1 gram). Carbon-12 is also the standard for all other atomic masses. Its nucleus contains 6 protons and 6 neutrons, giving a mass number of 12. Furthermore, carbon is the basic element of organic life because of its unique ability among all the elements to form long and complex chains or molecules. No other element even comes close in this ability. Without carbon there would be no life.
According to current theory, the Big Bang did not produce significant amounts of carbon or other heavy elements (heavier than lithium). Mostly the Big Bang produced hydrogen and helium (constituent elements of stars, including our sun). The heavier elements need extremely high temperatures to fuse the lighter nuclei of hydrogen and helium to make heavier nuclei, but the Big Bang had “cooled” below that temperature after only about 10 seconds. After the Big Bang, only very dense exploding stars were capable of generating such high temperatures and pouring out heavy elements. So all the carbon in your body was once part of an exploding star (as was all the oxygen, nitrogen, calcium, potassium iron, etc). Congratulations – You Are Stardust.
If I go with molecules based on carbon-12 as today’s theme I have unlimited possibilities for recipes. Everything we eat, with the exception of salt, is organic (based on carbon). That’s not especially promising or limiting. But if we focus on Avogadro we can narrow things down. Avogadro’s full name was Lorenzo Romano Amedeo Carlo Avogadro di Quaregna e di Cerreto, Count of Quaregna and Cerreto (9 August 1776 – 9 July 1856). He was born in Turin in the Piedmont region of northern Italy – then part of the kingdom of Sardinia. Avogadro graduated in ecclesiastical law at the late age of 31 and began to practice thereafter. But he soon became attracted to physics and mathematics and in 1809 started teaching them at a liceo (high school) in Vercelli, where his family lived and had some property.
In 1811, he published an article with the title Essai d’une manière de déterminer les masses relatives des molécules élémentaires des corps, et les proportions selon lesquelles elles entrent dans ces combinaisons (“Essay on Determining the Relative Masses of the Elementary Molecules of Bodies and the Proportions by Which They Enter These Combinations”), which contains Avogadro’s central hypothesis on atomic mass. In 1820, he became a professor of physics at the University of Turin. Avogadro was active in the revolutionary movement of March 1821. As a result, he lost his chair in 1823 (or, as the university officially declared, it was “very glad to allow this interesting scientist to take a rest from heavy teaching duties, in order to be able to give better attention to his researches”). Eventually, King Charles Albert granted a Constitution (Statuto Albertino) in 1848. Well before this, Avogadro had been recalled to the university in Turin in 1833, where he taught for another twenty years.
Turin is most famous in Italy for its chocolate. Turin chocolate firms make all manner of chocolate products but are famous for Gianduiotto, named after Gianduja, a local Commedia dell’arte mask. The city is also known for bicerin, a traditional hot drink made of espresso, drinking chocolate and whole milk served layered in a small rounded glass. Every year Turin organizes CioccolaTÒ, a two-week chocolate festival run with the main Piedmontese chocolate producers, such as Caffarel, Streglio, Venchi and others.
I’m not a big fan of chocolate, and even if I were to give you a recipe you’d need to come to Italy for the right ingredients (and atmosphere). The Piedmont region does have some savory dishes I like, however. One is paniscia, which in Italy is called “risotto” but is, in reality, a creamy version of the Hispanic staple, rice and beans. Paniscia originates in Novara, to the west of Turin, but is quite commonly found throughout Piedmont (and impossible to find elsewhere in Italy). You’ll have to make do with what you can find for meat/pork products. The whole Po Valley is famous for its regional sausages and hams. Use one or two semi-cured Italian pork sausages. Local ones in Piedmont are salam d’la duja, a somewhat soft, half-cured sausage finished submerged in pig fat, like a confit, and fidighina, with pig’s liver. Lardo is cured pork fat, for which you can substitute lard, and cotenna is cured pig skin, which you can replace with roast pork skin. Local cooks often use carnaroli rice rather than the more usual arborio rice used in risotto because it cooks up creamier.
¾ cup dried borlotti beans
½ head savoy cabbage, shredded
2 ribs celery, chopped
1 leek, cleaned well and chopped
4 oz Italian semi-cured sausage, diced
4 oz lardo or pork fat, diced
4 oz cooked pork skin, diced
¾ cup carnaroli (or arborio) rice
1 cup Italian red wine
1 tbspn butter (plus extra)
2 oz Parmigiano-Reggiano cheese
salt and pepper
Cover the beans with cold water and soak them overnight.
Drain the beans and put them in a pot with the cabbage, celery, leek and salt to taste. Cover with water and bring to a simmer. Cook until the beans are tender but not completely cooked (around 2 hours). Keep the pot warm.
Place the meats in a wide, deep, heavy skillet and warm over medium-high heat. When the lardo starts to melt, add the rice. Stir with a wooden spoon to coat the rice with the fat. Continue to cook for 2 to 3 minutes. Add the wine and allow it to reduce, stirring constantly.
Now you begin the risotto-making process which takes time and experience. Place on ladle of the bean broth in the skillet and stir. Controlling the heat is crucial. The broth should not bubble vigorously nor simmer listlessly. Somewhere in between. When the broth has nearly been absorbed add another ladleful. Keep stirring as the rice cooks and add more broth as it is absorbed. After about 15 minutes check the rice. It should be close to cooked. Start adding the beans and vegetables with the broth towards the last 5 minutes. The rice should be al dente and the whole mixture will have a creamy texture.
Remove the skillet from the heat, let it rest for 5 minutes, then add the butter and cheese. Stir thoroughly until the butter and cheese melt and are incorporated. Serve immediately