CHEM 106

This week we learned about how the anthocyanin and flavonol pigments in red cabbage act as indicators.  The anthocyanins turn reddish pink under acidic conditions and blue under more basic conditions, whereas the flavonols were colorless under acidic conditions and yellow under basic conditions.  This resulted in pinkish colors under acidic conditions (reddish pink + colorless pigments) and green colors under basic conditions (blue + yellow).  One of the materials we got to experiment with was household bleach, which, like most cleaning agents, is basic.  However, we all noticed an interesting effect: bleach did turn the cabbage paper green.

More accurately, the bleach turned the paper green at first.  Then the colors quickly faded away, resulting in pure white.  I decided to do a little research this week on why this happens: how does bleach work?

Household bleach is commonly made up of sodium hypochlorite (NaOCl) in water.  The sodium hypochlorite tends to dissociate into sodium ions (Na⁺) and hypochlorite ions (^–OCl), and the hypochlorite ion is the active ingredient.  It is able to produce a reaction known as oxidation, which can break some key bonds in colorful molecules.  When these bonds are broken, the molecule no longer reflects light in the same way, and the substance it makes up becomes colorless.

How does this play out for red cabbage?  The anthocyanin and flavonol structures under basic conditions are shown below.

The color of these compounds comes from the highly conjugated system of rings they contain (the places where there are lots of alternating single and double bonds).  The wavelength of light that is reflected/absorbed depends on the electrons and how they form bonds in the molecules; these types of bonds tend to produce very vibrant colors.

From what I can tell, the oxidation reaction from the hypochlorite ion breaks open the rings in the upper right corner of the molecules.  This disrupts the conjugated system of bonds, destroying their colorful effect and leaving our paper white rather than green.

Last class we saw for ourselves that water and oil do not mix. This is due to the fact that water is polar and oil is non-polar. Water molecules form strong hydrogen bonds with each other and are not as attracted to non-polar oil molecules. Shunned, oil separates from water and remains as droplets or a slick at the water’s surface, where there is the least amount of interaction with water molecules.

I was curious about ways that the “like dissolves like” rule could be bent and found this video ( https://www.youtube.com/watch?v=tETrZUhqaQo ) about some of the emulsifiers used in cooking to combine oil and vinegar. Vinegar is a polar substance made mostly of water and will separate from oil only minutes after whisking. An emulsifying agent like lecithin (found in egg yolks) can prevent this separation so that oil remains dispersed and suspended in the vinegar. This makes for a tastier vinaigrette.

As the video explains, lecithin (like soap) has a hydrophilic end as well as a hydrophobic end. The hydrophobic end is compatible with non-polar oil molecules, while the hydrophilic end of lecithin is compatible with polar vinegar molecules. This allows lecithin to form a kind of shield around droplets of oil, which makes it unnecessary for them to flee to the vinegar’s surface or recombine with other oil droplets.

I remember seeing ‘soy lecithin’ on many food labels. Apparently it’s cheap, which boosts its popularity amongst food manufacturers in need of an emulsifier. Also, it probably doesn’t have as noticeable a taste as mustard or egg.

Last week Mala Radhakrishnan came to our class to teach us a bit of chemistry and introduce us to “chemistry poetry”. Mala explained that she first came upon this intersection between chemistry and poetry when she was coming up with creative stories to uniquely explain concepts to her high school chemistry class. On a similar note, in “Genomics, Cellomics and… Poetryomics?”, one of the articles for this week, Robery Deyes writes about The Human Genre Project. This project’s goal is to collect works from the public to create an educational resource used to artistically teach people about the human genome. In this article I learned that over recent years poetry has caught the eye of those interested in using new and accessible modes for teaching scientific concepts.
Intrigued, I decided to do a bit of my own research on “scientific poetry” and I came upon a very relevant article, “The science of poetry, the poetry of science” : http://www.theguardian.com/books/2011/dec/09/ruth-padel-science-poetry . In this piece Ruth Padel writes about the relationship between poetry and science, and argues, against critics, that the two surprisingly have a lot in common. Padel writes that “science was born in poetry”. She explains that poetry was the earliest written mode through which humans pondered what the world was made of and how it was created; both science and poetry unveil “the secrets of nature”. Padel explains that science and poetry are both dependent on metaphor. She goes even further to claim that both “get at a universal insight or law through the particular”. Finally, Padel introduces the idea that both poetry and science “can tolerate uncertainty. They have a modesty in common: they do not have to say they’re right. True, perhaps. Or just truer”. This last similarity I found to be quite interesting and crucial to the pairing of science and poetry.

Professor Radhakrishnan showed us how oil and food coloring interacted with water and surface tension. She also discussed how soap works. Soaps are made up of long molecules with one end that loves water, and another that does not. This enables the soap to break apart greasy molecules that are often hard to clean.

I found a video that connects both of these topics. It shows how the surface tension of milk is affected by Softsoap, Gain, Perfect Coat (a dog shampoo), body lotion, and Dirt Devil. In order to see the effects that each different soap has on the milk, the experimenter puts food dye in the milk with a q-tip. The experimenter is able to make intricate designs by adding soap to milk with food dye in it. Each soap the experimenter uses has a different visual effect on the water. I assume the different visual effect each soap has on the water somehow represents the different chemical composition of each soap used.

Milk is unlike water in that it contains more lipids. Soap when added to the surface of milk dissolves the fat and lowers the surface tension in that place. The surface tension of the milk around the soap droplet is higher. The difference in surface tension creates the patterns and colors of the dye in the milk, instead of the colors all just mixing together.

Warning: the music in the video is weird.

https://www.youtube.com/watch?v=X4vA3Agdd6A

http://www.coolscience.org/CoolScience/KidScientists/tiedyemilk.htm

This week my art is from an experiment I have conducted many times.  While I did not have the materials to create the experiment again this past week, I found this image online of its execution.

Corn Starch Experiment

I was inspired by our discussion of when an element is a solid, liquid, or gas.  The experiment is to mix water, food coloring (for artistic purposes… the food colorring can be fully mixed in or can remain uneven to add a marbled effect), and corn starch.  The result is a mixture that seems to be a solid when sitting still in a container, but a liquid when you try to hold it in the air, as it will seep through your fingers.  This mix is referred to as ‘quicksand.’  The chemistry behind the substance is that it is a “suspension” meaning a mixture of both a liquid and a solid.

In reading the Alan Alda, Spokesman for Science article, I found myself making connections through the ‘decision’ of to be interested in science or not.  Growing up, both inside and out of school, it seemed the favorite question was to ask was ‘what’s your favorite subject?’  I would typically respond with the response ‘math’ and ‘art;’ however, as I got older, the response to this became, ‘oh, so you like science as well?’ The underlying fact was that I liked some science; however, thought that you either liked math and science or creativity, history, literature, and arts.  This very clear distinction deterred me, as Alda says did for him as well; however, his scientific interests remained present through his choice of artistic ‘expression’ in his leisurely literature selections.  I believe there should be more TV shows and media outlets such as Robert Deyes’ Poem, The Hierarchical Life, and Professor Radhakrishnan’s poetry that are both entertaining and informative.

This past section also introduced the various reactions with different combinations of polar and non-polar elements.  ‘Like dissolves like,’ meaning that polar dissolves polar and non-polar dissolves non-polar.  This saying expanded on the simple understanding that various atoms don’t mix with others which results in the ‘layered’ appearance of certain combinations.  I now understand that the reason behind the layers is that atoms of variant polarities want to have the least amount of exposure with each other and the ‘layered’ effect is the most minimizing solution.

At this point, we are all too familiar with the snow that surrounds us. Those of us who spend time driving also know the snow to be the reason that the roads deteriorate so much each winter. Snow falls and covers the roads. Then, the snow melts on the roads because of the heat of continual driving (addition of kinetic energy) and seeps into small cracks in the pavement. Temperatures then drop and the water that melted from the snow in the cracks of the pavement expands as explained in the Brown chapter. When it freezes, water expands. Ice is of a lower density than water and thus takes up more space as the molecules stop moving. This freezing causes cracks and potholes to form and grow as the water beneath the surface of the pavement expands and contracts as the temperature varies.

I also looked into why salt is used during the winter to prevent the formation of ice. Salt lowers the freezing point of water, 32°F/ 0°C. If salt is added, that temperature drops. This is one of the reasons that we don’t see the ocean or salty rivers freezing as quickly or easily as fresh bodies of water. Road salt is polar and thus can be dissolved by water (since water is polar and likes dissolve likes) and will lower its freezing point. A water solution that is 10% salt will freeze at 20°F or -6°C and 20% saline will freeze at 2°F or -16°C—each additional 10% will result in a 10°C cooler freezing temperature.

It is interesting how these two phenomena can be explained by what we learned in class and read about over the past week. I’d be interested to know more about how different pressures affect these phenomena if at all.

When I was reading Professor Conway’s article of doing science and making art, I was reminded of Leonardo Da Vinci. There was recently an article in The Guardian arguing whether Da Vinci was a great artist or a great scientist. What I found extremely interesting was that the autor proposed that Da Vinci was “neither, both”. I believe that Da Vinci encapsulates that seemingly great divide between artists and scientists, a divide that Professor Conway attempts to reduce through his deduction that art has a specific cognitive process. Conway suggests that Picasso’s portraits were able to capture the essence of their subjects because of a lifetime of cognitive observations and that artists like Cezanne were extremely scientific in their choice of color and would rather leave blank spots than just randomly allocate a color. Similarly, one of Da Vinci’s most famous paintings, ‘The Vitruvian’ man perfectly captures the proportions of a human being as it is based on specific, accurate observations. Thus Da Vinci was actually at his most scientific when he was being an artist. This was when he used the actual science process of making observations and telling a story. In fact, his observations were so accurate that recently a doctor in Cambridge redesigned an aspect of heart surgery after studying Da Vinci’s depictions of a dissected heart

(Link: http://news.bbc.co.uk/2/hi/health/4289204.stm.)

Thus, it is extremely interesting to see how interlinked science is with art. While I had always known that there was a science to color choices, and as Jocelyn’s presentation depicted, there is such a big scienific component to the conservation of paintings, I had never even considered Professor Conaway’s proposal that the very essence of art is scientific; that with artists like Cezanne and Picasso, no stroke is random, no portrait is drawn without hours of careful observations; that with artists like Da Vinci, even the portrayal of scientific depictions can be artistic to capture the true essence of the object.

I had always considered cooking an art but was a little surprised at the level of scientific process involved. The green bean acidity test reignited my interest in molecular gastronomy. I was shocked to realize that many michelin starred restaurants (for example, The Fat Duck in the UK) actually had laboratories where chefs experiment with food and are encouraged to use scientific methods (for example, hypothesis testing) when creating new dishes. I believe that this area accurately represents the intersection of science and art – chefs routinely don the roles of scientists, and like many chemists, create new substances (dishes) by combining many different ‘elements’ (or ingredients) in a chemical reaction (heat or ice).

I really enjoyed watching Heston Blumenthal’s video below:

I would be further interested in experimenting with using different temperatures, and really seeing the effect of too much heat or too little on changing the flavor of the dish. I would also be interested in learning how heat or ice effects the taste that your dish is aiming to achieve, for example, whether tartness requires a different temperature than achieving a specific level of spiciness, or whether flavors depend more on the actual ingredients being used. Last week’s reading really opened my eyes to the potential laboratory that the kitchen represents, and like the scientific experiments I conducted in my high school, I would be interested in conducting similar experiments in the kitchen, and identying the effect of temperature on taste.