Happy Birthday Henri Le Chatelier

Henri Le Chatelier, born October 8, 1850.  Le Chatelier is most famous for the law on chemical equilibrium which bears his name: If a chemical system at equilibrium experiences a change in concentration, temperature, or total pressure, the equilibrium will shift in order to minimize that change.

Less Newt

Organic synthesis is a lot like witchcraft...but with less newt.

Happy Birthday John Dalton

John Dalton, born September 6, 1766, was an English chemist known for his Atomic Theory which had the following five points:

1. Elements are made of tiny particles called atoms.
2. All atoms of a given element are identical.
3. The atoms of a given element are different from those of any other element.
4. Atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative numbers of types of atoms.
5. Atoms cannot be created, divided into smaller particles, nor destroyed in the chemical process. A chemical reaction simply changes the way atoms are grouped together.  

Unfortunately, Dalton had an additional statement that prevented his theory from being accepted for many years: When atoms combine in only one ratio, "..it must be presumed to be a binary one, unless some cause appear to the contrary."

Dalton had no evidence to support this statement from his theory and it caused him to wrongly assume that the formula for water was OH and ammonia was NH. Because of this, Dalton's experimental data did not support most of the conclusions he drew from it.

Amazingly, all but two of the 200 year old statements in Dalton's Atomic Theory are still believed to be true by scientists today. The statement "Atoms cannot be subdivided, created, or destroyed into smaller particles when they are combined, separated, or rearranged in chemical reactions" is inconsistent with the existence of nuclear fusion and fission, although such processes are nuclear reactions, not chemical reactions. In addition, the statement "All atoms of a given element are identical in their physical and chemical properties" is not precisely true, as the different isotopes of an element have varying numbers of neutrons in their nuclei, though the number of protons remains consistent.

Dalton's method for representing the "elements or ultimate particles"

Figure name weight

1. Hydrogen 1
2. Azote 5
3. Carbone or charcoal 5
4. Oxygen 7
5. Phosphorus 9
6. Sulpher 13
7. Magnesia 20
8. Lime 23
9. Soda 28
10. Potash 42
11. Strontites 46
12. Barytes 68
13. Iron 38
14. Zinc 56
15. Copper 56
16. Lead 95
17. Silver 100
18. Platina 100
19. Gold 140
20. Mercury 167
21. An atom of water or steam, composed of 1 of oxygen and 1 of hydrogen, retained in physical contact by a strong affinity, and supposed to be surrounded by a common atmosphere of heat; its relative weight = 8 
22. An atom of ammonia, composed of 1 of azote and 1 of hydrogen -6
23. An atom of nitrous gas composed of 1 of azote and 1 of oxygen - 12
24. An atom of olefiant gas, composed of 1 of carbone and 1 of hydrogen-6 
25. An atom of carbonic oxide composed of 1 of carbone and 1 of oxygen -12
26. An atom of nitrous oxide, 2 azote + 1 oxygen - 17
27. An atom of nitric acid. 1 azote + 2 oxygen -19
28. An atom of carbonic acid, 1 carbone + 2 oxygen-19
29. An atom of carburetted hydrogen, 1 carbone + 2 hydrogen-7
30. An atom of oxynitric acid, 1 azote + 3 oxygen-26
31. An atom of sulphuric acid, 1 sulphur + 3 oxygen-34
32. An atom of sulphuretted hydrogen, 1 sulphur + 3 hydrogen - 15
33. An atom of alcohol, 3 carhone + 1 hydrogen - 16
34. An atom of nitrous acid, 1 nitric acid + 1 nitrous gas - 31
35. An atom of acetous acid, 2 carbone + 2 water - 26
36. An atom of nitrate of ammonia, 1 nitric acid + 1ammonia + 1 water-33
37. An atom of sugar, 1 alcohol + 1 carbonic arid - 35

Chemistry is Painless

Click to enlarge.

Happy Birthday Antoine Lavoisier

Antoine Lavoisier, born August 26, 1743, French chemist and one of the fathers of modern chemistry.  He brought chemical experimentation from the philosophical alchemists to the scientific chemists.  He stated the first version of the law of conservation of mass, co-discovered, recognized, and named oxygen (1778), as well as hydrogen, disproved the phlogiston theory, introduced the metric system, wrote the first extensive list of elements, and helped to reform chemical nomenclature all before being beheaded on 8 May 1794 in Paris, at the age of 50.

Happy Birthday Amedeo Avogadro

Amedeo Avogadro, born August 9, 1776, was an Italian chemist known for his work on the theory of molarity and molecular weight.  While he didn’t discover the number of particles in one mole of a substance, 6.022×10²³, is now know as Avogadro’s number.

(edit:spelling)

I have Mass. You have Mass...

Man: I have mass.  You have mass.  We are naturally attracted.
Woman: It's a purely physical attraction.

Happy Birthday Rosalind Elsie Franklin

Rosalind Elsie Franklin, born July 25, 1920, was a Physical chemist and crystallographer who worked on the X-ray diffraction images of DNA which formed a basis of Watson and Crick's hypothesis of the double helical structure of DNA in their 1953 publication.  When published in its own article along side Watson and Crick’s, her data constituted critical evidence of their hypothesis.  Later, she led pioneering work on the tobacco mosaic and polio viruses.

Test Tube Science: Black Bean Indicator

There are lots of acid/base indicators available in the home.  The one I'm going to talk about today is an indicator made from black beans.

Marcelle was making a big batch of feijoada and started the black beans soaking the night before we were going to have it for dinner.  As she was preparing to pour off the blue/purple water they had soaked in I asked her to save some for me.

The dinner was delicious. And I decided that I'd see what colors I could come up with after dinner.  In the picture below you can see the spectrum of colors obtained from my black bean juice with vinegar and baking soda.

Black bean indicator: acidic on the left, neutral in the middle and basic on the right.

To make your own indicator take 10-15 dry black beans put them in a test tube and cover them with water.  Let them soak for 10-12 hours for the most concentrated solution.  Now you can remove the water and use it as an indicator in other solutions.  Dilute the black bean juice 1 part juice to 4 parts test solution.

If you want to get some indicator in 10 minutes instead of 10 hours you can soak the beans in 70% isopropyl alcohol.  The alcohol will make a solution much faster.

Acid, neutral, and basic forms of anthocyanins.

The primary color changing molecules in black beans are anthocyanins. As the pH of the solution changes the structure of the molecule changes.  This changes its absorption spectrum thus changing the color of the solution. These reactions are in equilibrium making them great natural indicators.

U and I Together

Man: If I were designing the periodic table I'd put U and I together.
Woman: A then both Mendeleev and I would cry.