Tuesday, June 26, 2012

The Ancient Art Of Brewing And The Chemistry Behind It!

According to archaeological evidence, brewing was first done by people living in ancient Mesopotamia around the 5th millennium B.C.  The oldest beer recipe comes from a 3900-year old Sumerian poem honoring the brewing goddess, Ninkasi.  More recent, however, is my summer break which allows me time to experiment with brewing.  This year I decided on a blueberry concoction since I have been seeing fresh fruits all over the place.  As added bonus, my son who loves doing things in the kitchen, assisted me with this endeavor.  Last month we made strawberry ice cream from our excess handpicked strawberries - look for a "chemistry of ice cream post" later in the summer.

The ingredients consist of four main parts:
1) malted grain - barley, wheat, oats, corn, or rice that is soaked with water until germination begins.
2) hops - the flower of the humulus plant that is used for aroma and more importantly adds bitterness which balances the sweetness of the malt.
3) yeast - a type of fungi which converts fermentable sugars into alcohol.
4) water - H2O.

Our Ingredients:
As you can see I cheat a little bit as I brew from a kit (Mr. Beer).  They have numerous recipes and suggestions to choose from.  The brew that we are making is based on the recipe for Jazzberry Ram but we are substituting blueberries in syrup for raspberries in syrup (I like blueberries more).  

Step 1 - Decontamination:
All equipment must be cleaned and sanitized before fermenting.  The cleaner contains sodium percarbonate (2Na2CO3*3H2O2) which is a white solid that releases the oxidizing agent hydrogen peroxide (H2O2when dissolved in water.

Step 2 - Create the Wort:
The wort is the term used for the mixture that is the unfermented beer.  In our case we first boiled water (4 cups) and mixed the Booster from the kit which consists of dextrose (C6H12O6) and maltodextrins (a polysaccharide consisting of multiple dextrose units).  The Booster provided additional fermentable and unfermentable sugars to the wort.  We also added a packet of Saaz Pellet Hops to give a spicy flavor to the wort.  As the powder is added to the water it forms a cool looking soft crystalline mass and before dissolving completely.

After boiling, we added a can of Linebacker Doppel Bock from the kit which is a gooey mixture of already malted grains and hops.  This is the wort.

Step 3 - Final Mixing:

To the decontaminated fermentation chamber (keg) we added cool water (4 quarts) from the faucet.  The water has to be cool as the hot wort could damage the plastic keg.  You might be tempted to use distilled water or water purified by reverse osmosis but it lacks important nutrients for the yeast.  On that note, however, make sure your water is not polluted and tastes good.  We then added the warm wort mixture and the can of blueberries to the keg holding the cool water.  Next we added more water to the mixture until the total volume was 8.5 quarts.  Finally we added the small packet of dry yeast, stirred the wort, and placed it into to the basement so it can ferment.

Fermentation (what's cooking in my basement):
Fermentation is a metabolic (biological) process by which sugars are converted ethanol and carbon dioxide.  The chemical reactions look like this:

1)  C12H22O11    +    H2O    +     Invertase        =>        2C6H12O6
     (sucrose)                        (enzyme in yeast)              (glucose)

2)  2C6H12O6    +    Zymase        =>        4C2H5OH    +    4CO2
     (glucose)        (enzyme in yeast)         (ethanol)         (carbon dioxide)

According the reactions shown above, one mole of sucrose produces four moles of ethanol and carbon dioxide.

The End! Or until bottling...

wikipedia - Good general info for initial an source.
Maltose Express - Good local source for serious brewing.
GlenRo - Good local source for general info.
Mr. Beer - Good source for info and for brewing without leaving your house.

Friday, June 15, 2012


I have been assigning a Final Project for the the students to complete during the last week of school before final exams for the past three years.  The end of the year project morphed out of my original assignment which I gave after the first month of school and was to have students research a scientist who contributed to atomic theory.  This became rather boring for me since students kept choosing the same scientists from year-to-year.  Add to that, the students have not had that much chemistry yet so their knowledge was limited.  At the suggestion of Mike Sirowich, a.k.a. The Physics Teacher at Seymour, I moved the project to the end of the year for a couple reasons: 1) the students have more chemistry behind them so they can go more in depth with their research and 2) it is very difficult to hold the students attention during the final weeks of the school year.

Another change that I made from the early days was to open the topic of study list.  In its new form students can choose from the following list:

·      Explore the life and contributions of a famous chemist/scientist
·      A unit we have covered this year (atomic theory, electrons, organic molecules, etc.)
·      A topic and integrate content from several units (synthesis of a compound, distillation, refrigeration, etc.)
·      Medical or other devices used in chemistry (CAT scans, X-ray, PET, MRI, electron microscopy, GC, GC/MS, etc.)
·      Other topic/experiment with instructor approval 

This new approach has given the students more choices in what they want to do as some would rather do an experiment or research a topic.  Also new this year , thanks Mike, was having each student who did a group project assess each their team members.  They simply handed me a sheet of paper indicating what they did and what the other members DID or DID NOT do.   The last of Mike's ideas incorporated into the project was to create Google Form where each student comments and rates each presentation at the conclusion.  Students were able to link to the short form with cell phones or laptops.  This kept most everyone's interest throughout the talks and provided positive feedback to the students.

Of the 36 total projects, 12 were of scientists, 4 involved cooking or baking, 7 involved students performing experiments, and 11 were of various chemistry topics.  I learned many new things this year and found a new demo.

Students from Period A did a presentation on Newton, another team did Galileo, and  a third complimented the first two be doing the broad topic of Relativity.

Students from Period B did reaction experiments using Mentos and soda while another group made and filmed the chemistry of baking chocolate covered cupcakes.  They were delicious!

Students from Period G focused on topics such as X-rays and chemotherapy, however, one group baked pizza while another group attempted to see if there was a relation between Mentos and acidity in soda.  Could Mentos be used an indicator?  The results were indicated that it was not a good indicator.

Students from Period H mainly did scientists such as Einstein and Curie but one group made ice cream and another person baked bread.  Unfortunately she forgot to convert to Fahrenheit so we could not sample the product.

My AP Chem class (Period C) students focused on experimentation such as Mentos, chromatography, fire works, and wood gas.  Another student found a penny from the 1800s in her backyard and did experiments cleaning it.  The results indicate 6.0 M acetic acid with a concentrated salt solution works the best.  Lastly, a student synthesized nitrogen triiodide and then let it do its thing.  It is so unstable that when it dries any perturbation sets it off.  Spectators are treated to a loud explosion with purple smoke.  Unfortunately you never know when it goes off as the first batch went off unexpectedly during a different class.  I found a new Demo!

I would love to show off the students with their creations but our school district, as most are, is hesitant when showing students or even printing their names without parental notification.  In order to get that I would have to fill out paperwork in triplicate and send it home for the  parents to fill out as well.  Hopefully I will be able edit out names and such to show off some of their work.

Friday, June 8, 2012

What is a Flame

Ben Ames, 31, from Kansas City, Mo and current physics graduate student at University of Innsbruck in Austria answers this question in the following link:  
[click the link and enjoy]

What is a Flame.

The explanation is the best I have heard due in part to its visual graphics using Legos and its simple explanations.  The video was developed in response to a contest put together by Alan Alda who is currently involved with and a founder for the Center for Communicating Science at Stony Brook University.  The selection took place at the World Science Festival in New York.  

For more information: In Winning Definition of ‘Flame,’ Jargon Melts Away by Kenneth Chang, NYTimes and The Winning Answer to a Burning Question at NPR.

Friday, June 1, 2012

Green Flame Reaction

I performed a favorite demonstration for my students recently where a white powder (boric acid) is mixed with small amount of methanol in a flask and then ignited, the result is an eerie green flame.   This year, however, I experimented with the time I let for the reaction to take place.  The results were noticeable.

Video 1 shows the first trial where boric acid and methanol were mixed for approximately 45 seconds before it was ignited.  The green flame lasted approximately 1 second the flame is much more green in person).

Video 2 shows the second trial where the mixture was shaken for approximately 74 seconds and then ignited.  The green flame in this trial lasted approximately 3 seconds.

I varied the reaction times for two other classes and obtained similar results.  So there you have it, vigorously shaking the mixture for longer times leads to a longer burning time for the green boric acid ester.

Boric acid has a wide range of uses other than serving as neat demos for chem teachers such as rat poison, antiseptics, acne prevention, and others.  Boric acid trimethylester (trimethyl borate) is used as a solvent for the production of waxes and varnish and such.

For those interested, the reaction is as follows:

 H3BO3 + 3CH3OH => B(H3CO)3 + 3H2O

This demonstration was modified from BangsFlashes, and Explosions – Illustrated Guide to Chemistry Demonstrations. ©2005 Chris Schrempp and ExploScience.com.