Moles In Food or Drinks Lab

Determining Moles in Food or Drinks Lab (no, not the animal hopefully…)

Please make your answers stick out by coloring, bolding or italicizing them. Objectives: - to identify elements and compounds in foods from the nutrition label - to convert between units of grams, milligrams, moles, molecules, atoms and milliliters

using conversion factor method - to determine mass of an item that can’t sit directly on a balance/scale. Materials needed:

- A food item containing sodium or potassium listed in grams or milligrams on the nutrition label

- A food item containing caffeine, cholesterol or sugar listed in grams or milligrams on the nutrition label. - Balance, beaker, graduated cylinder - water - another liquid that is a compound, not a mixture. Options include: Rubbing alcohol (Isopropanol is C3H7OH), hard liquor like vodka (assume its pure ethanol, C2H5OH) or hydrogen peroxide, H2O2. [Milk, juice, pop and most other drinks are mixtures, not compounds, so don’t use those.]

Safety considerations:    Small particles can become lodged in the eye. Safety goggles are recommended for this lab especially if you are using food packages that are open. Flush with water if particles become lodged in eyes.      

Introduction:  

Like a “dozen” stands for the number 12, a “mole” stands for the number 6.022 x 1023. Since

atoms and molecules are so small, we use the “mole” to

count them. The mass of 1 mole of atoms of a particular element is called the molar mass and is the same as the average atomic

mass in grams. So the molar mass for an element can be

directly found on the periodic table. 1 mole of oxygen atoms weighs 15.999g. 1 mole of hydrogen atoms weighs 1.008 g etc.

A compound’s molar mass can be found by adding up the elemental molar masses multiplied by each corresponding

subscript as seen to the right.

The labels on a food product list components in grams and milligrams. It is possible to convert those values to moles and

then figure out how many molecules and atoms are in the food.

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DIRECTIONS:  SHOW  ALL  WORK  FOR  ALL  CALCULATIONS.    INCLUDE  UNITS  IN  WORK  SHOWN  AS   WELL  AS  IN  THE  ANSWER.  Color/bold/italicize  your  answers.   Example: How many minutes are in a week? Start with the given information: 1 week Determine the conversion factors needed: 1week=7days, 1 day=24hr, 1hr=60min Use parentheses to show multiplication. The denominator of one conversion factor will cancel the numerator of a different unit: (1week)*(7days/1week)*(24hr/1day)*(60min/1hr) Give the numerical answer with a unit:

(1week)*(7days/1week)*(24hr/1day)*(60min/1hr) = 10080 minutes This last line of multiplication and answer with unit is all you need to type. Technically, the “*” symbol is not needed since two parentheses next to each other implies multiplication already.

PART A: FOOD LABELS Sample Procedure: Verify that the answers to these questions are correct based on the food label provided (so there is nothing to type for your answer here, just be sure you understand how answer obtained):

A. Report the name/description of product. Answer: Box of Blue Moon Iguana Treats

B. Report the number of servings in the container. Answer: 22 servings

C. Report the component of interest (Choose from: sodium, potassium, caffeine, cholesterol or sugar – note, sugar is sucrose.) Answer: Caffeine

D. Report the mass of component per serving.

Answer: 0.56 mg per serving [This has 2 sig figs so my final answer will have 2 sig figs]

E. Report the element symbol or chemical formula of the component.

Answer: C8H10N4O2 (yes, I had to look up this one on the Internet) F. Report molar mass of the component to 2 decimal places.

Answer: 194.22 g/mole (I used answer to E and periodic table)

G. Convert the mass of component per serving into moles of that component per container. Show your work & report your answer to 2 sig figs. (22 servings/1 container)*(0.56 mg/serving)*(1g/1000mg)*(1mole/194.22 g) = 0.000063433 = 0.000063 moles/container

H. Convert this number of moles of compound to molecules of compound. Answer: (0.000063433 moles C8H10N4O2) * (6.022 x 1023 molecules/1 mole) = 3.8199 x 1019 molecules of caffeine = 3.8 x 1019 molecules of caffeine [Note, I kept a few

extra sig figs on the 0.000063433 to make sure I saved rounding until the final answer.]

I. Convert this number of molecules of compound to atoms of carbon. Answer: (3.8199 x 1019 molecules of caffeine) * (8 atoms of C/1 molecule caffeine) = 3.1 x 1020 C atoms [Note, I kept a few extra sig figs on the 3.8199 to make sure I saved

rounding until the final answer of 2 sig figs from letter D.]

1. Your turn. Find an item of food that has sodium or potassium in it, listed with grams or milligrams on the nutrition label and answer the questions below. SHOW ALL WORK WITH UNITS IN WORK & ANSWER

A. Report the name/description of product.

B. Report the number of servings in the container.

C. Report a component of interest (Choose from: sodium, potassium.)

D. Report the mass of component per serving.

E. Report the element symbol of the component.

F. Report molar mass of the component to 2 decimal places. G. Convert the mass of component per serving into moles of that component per container.

Show your work & report your answer to 2 sig figs. H. How many atoms of sodium or potassium are in this container? Since both sodium and

potassium are elements, there is no conversion to molecules first as there was in the example step H. We can go straight to atoms. Use 6.022x1023 atoms = 1 mole as the conversion factor to change moles to atoms. [And really we should say ions of sodium or potassium since you neutral Na atoms would explode in your stomach but you need Na+ ions (as in this example) to live.]

2. Your turn again. Find an item of food that has caffeine, cholesterol or sugar in it, listed in grams or milligrams on the nutrition label. Note, sugar may be called sucrose on a label. SHOW ALL WORK WITH UNITS INCLUDED IN WORK AND IN ANSWER

A. Report the name/description of product.

B. Report the number of servings in the container.

C. Report a component of interest (Choose from: caffeine, cholesterol or sugar.)

D. Report the mass of component per serving.

E. Report the chemical formula of the component.

F. Report molar mass of the component to 2 decimal places. G. Convert the mass of component per serving into moles of that component per container.

Show your work & report your answer to 2 sig figs. H. How many molecules of your component (caffeine, cholesterol or sugar) are in this

container? I. Using your previous answer, how many atoms of carbon are in the previous answer?

PART B: Moles of metals & liquids Procedure:

1) Part i: Find the mass of a large paper clip. 2) Separately, find the mass of a pre-1982 penny. (It needs to be before 1982 because

pennies are no longer mostly copper after 1982. If you really can’t find a pre-1982 penny, make note of that and use a more recent penny, assuming it is all zinc).

3) Perform the calculations asked for below in #4. 4) Part ii: Put an empty graduated cylinder on the balance, and then tare/zero it. Make sure

the balance says “0.0” before adding liquid. 5) Add 10.0mL (note the sig figs) of water to the graduated cylinder. You can use a pipet or

dropper to be more precise. It’s recommended to take the g.c. off the balance while pouring so that you don’t spill onto your balance.

6) Record the mass of the liquid. 7) Fill in the data table below. 8) Repeat steps 4-7 for another liquid (not water) that is a mostly compound, not a mixture.

Nothing is truly a pure compound but we will assume purity. Options include: Rubbing alcohol (assume it is pure isopropanol, C3H7OH), high-proof, hard liquor like vodka (assume its pure ethanol, C2H5OH) or hydrogen peroxide, (assume it is pure H2O2). [Milk, juice, pop and most other drinks are mixtures, not compounds, so don’t use those.] Oils, though possibly pure, aren’t recommended as they are difficult to clean out of your g.c.

  3. DATA:  

Part  i:     paper  clip     penny  

Mass of metal object    

  Part  ii:      

Liquid: Water   Other  liquid:  _________________  

Mass of 10.0 mL of liquid    

  QUESTIONS:  SHOW ALL WORK WITH UNITS INCLUDED IN WORK AND IN ANSWER  

4. Assume paper clips are pure Aluminum, how many atoms of Al are in your paper clip? Assuming pre-1982 pennies are pure copper, how many atoms of Cu are in your penny? (Note: if you use a more recent penny, you’ll have to assume the penny is all Zinc since it is only just coated in copper.) Which object has more atoms in it?

5. How many molecules are there in your 10.0 mL of water? How about in 10.0mL of your other liquid?

6. How many atoms of hydrogen are in your 10.0mL of water? How about in 10.0mL of your other liquid?

7. How many atoms of oxygen are in your 10.0mL of water? How about in 10.0mL of your other

liquid?

8. How many water molecules do you drink per day? Assume you drink 1.5 L of water. And density (H2O) = 1.0 g/mL. **Extra credit: Keep track of how much water you drink in a day and use that amount instead. For full extra credit, include the time of day and how much water you drank then. Add it all up and then figure out how many water molecules you drank.

  9. How many mL of water should you pour into a graduated cylinder to have one mole of water?

  Post-lab questions:    KEEP  SHOWING  WORK  INCLUDING  UNITS  

10. Go to www.goldprice.org and find the price of gold in grams (change the unit to grams). Using this number, what is the approximate dollar value of one mole of gold atoms? (Write your answer to the nearest cent.)

11. Which would you rather have, one mole of pennies (6.022 x 1023 pennies), or one mole of gold atoms (6.022 x 1023 atoms)? Write your answers as either “1 mole of pennies” or “1 mole of gold” and explain why.