Marvelous Mixtures Part 1, Sweet Southern Sol

In chemistry matter comes in two very broad categories, pure substances and mixtures. Pure substances are things like pure water, there is only one type of substance (atom or compound) present in any sample. Mixtures are everything else and are often described by whether or not the individual parts can be seen. If a mixture looks the same throughout it is called homogenous (like salt water). If it doesn't it is called heterogeneous (like a salad). I will talk about various kinds of mixtures that cover the whole spectrum at various points. Today we'll deal with a very specific type of homogenous mixture called a sol.

Homogenous mixtures are categorized by how large the pieces of the minor substance is. If the minor compound is an atom or molecule it is called a solution. If it is a little bigger, but small enough that the minor compound cannot be seen by the naked eye it is called a colloid. If it can be seen, it is known as a suspension. The different components can be solid, liquid, or gas and they don't have to be the same as each other. This is how we end up with all of the weird products that seem to be in between phases (like Jell-O). A sol is a very specific type of colloid where a solid is "dissolved" or "suspended" in a liquid. This is all in theory of course. In reality whenever a liquid has particles in it that don't separate out upon standing chemists will call it a solution. If the particles do separate out, it is referred to as a suspension.

Today the weather decided that we should have summer, real DC summer, a little early. We hit 90 degrees Fahrenheit (32 degrees Celsius or 305 Kelvin for those who spend all their time in a lab). So I decided to cool off with some of my sweet tea. A delicious and satisfyingly sweet sol. While the sugar does create a solution, the tea particles are too large for the mixture as a whole to be considered a solution, so a sol it is. And it is a sol that satisfies the soul.

Sweet Tea

Ingredients

4 cups water (plus enough to bring the final product up to a gallon)

3 family sized ice tea bags (or 12 normal sized tea bags)

a pinch of baking soda

1-1/3 cups sugar

Bring 4 cups of water to a boil. Remove from heat. Add a pinch of baking soda and 3 family sized tea bags. Cover and let sit for 15 min. Remove tea bags (you can throw them out at this point). Add sugar and stir until completely dissolved. Pour concentrate into a gallon sized pitcher and fill the rest of the way with water. Chill, pour, and enjoy!

Beyond Sodium Bicarbonate, aka Best Ever Brownies

Pancakes or cupcakes, muffins or cookies, baking soda or baking powder. They all contain one secret ingredient, sodium bicarbonate. This simple salt is also a simple base and is the ingredient that makes most batters rise. The most basic definition of an acid is a chemical that readily gives up a hydrogen atom. A base, on the other hand, is a chemical that accepts a hydrogen. Chemicals that do not fall into one of the two categories are neutral. In a kitchen, water is neutral. Acids include eggs, milk, buttermilk, vinegar, sour cream, yogurt, and cream of tartar. Bases include baking soda (aka sodium bicarbonate) and butter.

But why does baking soda work? In baking soda, the oxygen on the sodium bicarbonate (above) grabs on to a hydrogen from the acid creating an H2O (water) molecule which is very happy on its own and leaves the molecule. Which means that all that is left is CO2 (that's right, the green house gas we have all been hearing so much about). The heat causes both the steam and the CO2 to expand (more later on expanding gases) and the batter rises. Baking powder is simply a mix of baking soda (base) and cream of tartar (acid) with a little corn starch thrown in as a filler. When dissolved in the liquid part of your recipe they mix, creating the gas. And the reaction occurs at room temp, so it is best to use any batter as soon as possible after you mix the liquids and powders. You don't want all those glorious bubbles to escape.

The products of mixing an acid and a base in the right ratios are neutral, so every good chemistry lab will have a box of baking soda sitting around just in case someone spills acid. When I was in high school I happened to knock over a graduated cylinder of hydrochloric acid (bad stuff). My teacher came running over at top speed with a box of baking soda and covered everything, the table, my lab notebook, and a little bit of me, with baking soda to neutralize the spill. Sodium bicarbonate also helps to neutralize excess stomach acid so it is great in a pinch if you run out of Tums or Alka Seltzer.

Now for the food!

This is my favorite fancy brownie recipe (featuring sodium bicarbonate in the form of baking powder). Whenever I have surprise dinner guests these will find their way onto the table. I nearly always have the ingredients on hand and they are extremely easy to make. I discovered this recipe at Sugar Cooking (http://sugarcooking.blogspot.com/2009/08/cappuccino-brownies.html) and it was adapted from the book Bars and Squares by Jill Snider.

Cappuccino Brownies

Brownie

1 cup chocolate chips

1/2 cup butter

3/4 cup white sugar

1/4 cup packed brown sugar

1 teaspoon vanilla

2 eggs

1 cup flour

1 Tablespoon instant coffee powder

1 Tablespoon coca powder

1/2 teaspoon baking powder

1/2 teaspoon salt

Preheat oven to 350 degrees. Butter an 8x8 pan. In a medium bowl combine the flour, coffee powder, cocoa powder, baking powder, and salt. Set aside. Put chocolate chips and butter in a large bowl and set over a sauce pan of simmering water (aka a pour man's double broiler), stirring until smooth. Turn off the heat. Whisk in the sugars and vanilla. Remove from pan. Add eggs one at a time. Fold in flour mixture. Pour into the prepared pan and bake 30-35 minutes (my oven runs a bit hot, and I prefer my brownies on the softer side so I usually bake mine about 25-30 minutes). Cool completely.

Frosting

2-1/2 teaspoons instant coffee powder

2 cups confectioners sugar

1-2 Tablespoons milk

1/4 cup butter

In a bowl combine coffee powder and 1 Tablespoon milk, stirring to dissolve. Add butter and sugar and beat until creamy, adding milk as necessary to obtain the desired consistency (I usually add at least one more Tablespoon). Spread evenly over the cooled brownies. Chill completely.

Glaze

1 cup chocolate chips

1/3 cup whipping cream

Put chocolate chips and whipping cream in a bowl over a saucepan of simmering water, stirring constantly until smooth. Let cool to lukewarm. Spread over frosting. Chill until chocolate is set, about one hour (mine usually don't make it that long, but if you want them to be firm and stackable let them chill the full time).

*Note on my delicious blob above. I not only didn't let them chill enough, I also seemed to undercook my brownies. But, as the title says, at least I didn't blow anything up.

Chemistry Queen or Mad Scientist?

So this all started as an photography assignment and a curious spark. I was working in a Chemistry lab and cooking all the time. Cooking was my passion; chemistry was my life. I tried, in a single portfolio (still in progress), to show people who weren't in the lab that science isn't all that different from everyday life. I wanted to demystify chemistry and make it cool again. Like during the Cold War when the United States was the shinning star of technology and scientists were heros.* So here is my attempt. Every week or so I am going to try and figure out/explain, why things work in the kitchen using basic chemistry, physics and biology. The fact of the matter is I don't have a clue right now why anything works so I'll be in the weeds with the rest of you. I don't blame you at all if you skip the sciency stuff and go right for the recipes. And I really hope this doesn't turn into a repeat of Organic Chemistry (tears, frustration, failure, repeat). Recipes will be included, photos will happen, and I'll try really hard not to blow anything up.

*If you want to see something really cool, high tail it down to the Smithsonian American History Museum. They currently have an exhibit on American research and it is sitting right next to Julia Child's kitchen.