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: