Working with one sample at a time, add water to the glass one tablespoon at a time. Water should soak the sample from the bottom up. Count the number of tablespoons of water it takes to bring the water level up to the top of the sample. Record the amount in the chart. Calculate the porosity of each sample using this formula, and record the results in the table. “Total sample volume” is the amount of soil, sand, or pebbles in the sample. A half cup is equal to 8 tablespoons.
% porosity = (amount of water added to sample ÷ total sample volume) × 100

PEBBLES -

SAND -

SOIL -

1. Fill a drinking glass with a cup of water (1 cup =237 ml). Add sugar one teaspoon at a time until you have added 5 teaspoons. Stir and wait until each teaspoon dissolves completely. Between each teaspoon, take a sip and see how “the drink” tastes. After 5 teaspoons you will have added ~ 25 grams, i.e. slightly less than there is in one cup of coca-cola. After how many teaspoons is the drink pleasantly sweet? After how many teaspoons is it way too sweet?

2. Pour half of the sugar-water into a separate drinking class and put it aside for later.

3. To the remaining sugar water solution (~1/2 cup), add small amounts of vinegar, approximately 1/4 teaspoon at a time, taking a small taste after each addition. Keep track of how much vinegar you are adding. How much did you have to add for the drink to taste good to you? Put this glass aside for later comparison.

4. Now fill another drinking glass with half a cup of water (1/2 cup =120 ml), and add the same amount of vinegar that you added to the sugar-water in step 3 in order for it to taste delicious. In other words, you will now have three cups: one with sugar-water, one with sugar-vinegar-water, and one with vinegar-water. Have a taste of the vinegar-water. How does the vinegar-water taste compared to the sugar-vinegar-water drink? To the sugar-water drink?

This is the secret of Coca-Cola! Coca-cola contains a lot of sugar, probably way too much for most people to find tasty. But by adding acid (and some other flavors as well) you can get a tasty drink!

This is an example of the complex ways in which taste molecules can influence each other, and recipes often exploit this fact. By having different flavors play off each other, the crafty cook can adjust the overall flavor experience of a food. This is a similar reason to why some cooks add a bit of sugar to balance out the acidity of tomatoes in a tomato sauce. And Nathan Myhrvold, whom we will hear from later in this course, even goes so far as to add salt to red wine to make it taste better!

Questions:

1. Calculate how many moles of sugar per liter you added to your drink in step 1 before starting to add any vinegar. The molecular weight of sugar (i.e., sucrose) is 342 g/mol, and 1 teaspoon corresponds to approximately 5 grams. Enter your answer to two decimal places, and do not include units.

Teapoons pH 1/4 4.5 2x 1/4 4.2 3x 1/4 4.0 4x 1/4 3.9 5x 1/4 3.8 6x 1/4 3.7 7x 1/4 3.7 8x 1/4 3.6 9x 1/4 3.6 10x 1/4 3.5

2. Calculate the concentration of hydrogen ions in moles per liter in your drink after you added 1.5 tsp of vinegar. You can use the table above which approximates the pH when adding certain amounts of vinegar to water. Enter your answer to one non-zero digit, and do not include units.

 unanswered

3. How many times more sugar molecules are there than hydrogen ions in this drink?

Show detailed calculations and sketches to solve problems, we will get similar problems for the final exam. thank you!!!

Explanation:

indium, and thallium have three electrons i think

pre-sliced bread is a relatively recent development in baking technology. previous to that, it was always sold in a bakery in daily-made contiguous loaves with no wrapping, and was moderately perishable, usually being used with a day or two (which is why every bakery had a discounted “day-old” bread table.) therefore, pre-sliced bread would grow stale quickly. the hard crust provided a protective layer, and once the exposed dry slice left from the previous cut was removed, the interior was still soft.

what keeps bread soft is the moisture retained in the crumb (the light spongy part that’s not crust). the reason the crust develops is the surface of the dough gets exposed to hot dry air during baking which browns the outer layer and seals it, preventing all the moisture from escaping the dough. longer exposure to air will also eventually cause your bread to lose flavor and become stale.

people were used to cutting slices as they needed them and storing bread in a specially-made wooden or metal breadbox or pail with a lid to preserve it longer, but the first automatically sliced commercial loaves were produced on july 6, 1928, in chillicothe, missouri, using a machine invented by otto rohwedder, an iowa-born, missouri-based jeweler.[1] pre-sliced bread would indeed dry out, were it not for another 20th century technology: the plastic bag. bread could now be pre-sliced, and if the enclosing bag remains sealed as much as possible, the bread will remain soft and fresh for longer than if sitting unwrapped on a shelf or enclosed in a bread box that is not air-tight. sealed packaging meant bread could also be sold on store shelves and eliminate frequent trips to a bakery.

sealing bread in a plastic bag had another effect: the moisture in the loaf will re-distribute into the crust and soften it, which is sometimes more pleasing in a sandwich - especially for children whose teeth might not yet be strong enough to tear through a hard crust. a homemade loaf of bread can be sealed in a bag overnight and the crust will become soft like store-bought sandwich bread.

these were novel changes in how bread was produced and sold, which led to the coining of the phrase “the greatest thing since sliced bread.”