Percent Composition Lab                                                          Name: ____________________________

 

IS DOUBLE STUFFED REALLY DOUBLE STUFFED?

A specific brand of cookie (beginning with the letter O made by Mr. C) claims that their double-stuffed cookie contains twice the amount of filling as their regular brand. But is this claim really true?

 

Background Information:

Percent composition of a compound tells you the percent (by mass) of each element in the compound.  We determine percent composition by comparing the mass (grams) of each element in a compound to the entire mass (grams) of the whole compound. Then we multiply by 100 to turn the number into a percent.

 

For example, suppose you sleep seven hours each night.  What percentage of each day do you spend sleeping?  (Hint: Divide the number of hours you spend sleeping by the total number of hours in a day.  Then multiply the answer by 100 to get the percentage). Show your work below:

 

 

 

Purpose:  Calculate and compare the percent of cream filling, by mass,  of a regular versus a double stuffed Oreo cookie. Treat the Oreo cookie as one compound and the two parts (the cookie and the filling) as the two different elements.

 

Hypothesis: Double stuffed cookies contain twice the amount of creamy goodness

 

Materials: a scale, a metal scoopula, 1 regular cookie, 1 double stuffed cookie, paper towel

 

Procedures:

  1. Your teacher will give you one of each type of cookie. Do NOT eat them as you are in the CHEMISTRY LAB!!! Weigh the cookies separately and record this information in the table.
  2. Start breaking the cookies apart. You will have two piles for each type: one pile for the dough and one pile for the cream filling. Try to scrape off as much of the cream filling from the cookie dough without breaking the dough (and without taking too much dough into the cream filling pile). This can be delicate work so be careful.  (Do this again for the other type of cookie.)
  3. When you have your two distinctive piles, take the mass of the dough (for one type) and the cream filling (for one type). Record this information in the table. Do the same thing for the other type of cookie. The mass of the dough and the cream filling should add up to the mass of the intact cookie in Part 1. If not, you left some dough or cream filling behind and this can alter your results.

 

Data Table:

Type of cookie

Mass of cookie (g)

Mass of dough (g)

Mass of cream filling (g)

% composition of cream filling

Regular Stuffed

 

 

 

 

Double Stuffed

 

 

 

 

 

 

 

 

 

 

Conclusion: Is the hypothesis correct or are double stuffed cookies a rip-off? Explain your answer.

 

 

Questions:

  1. A factory makes gift-boxes that contain two pillows and one gold brick. The brick has a mass of 20 kg and each pillow has a mass of 1.0 kg.
    1. What is the mass percent of the pillows in each gift-box?

 

    1. What is the mass percent of the gold brick in the each gift-box?

 

 

  1. Determine the percent composition of each of the following compounds:
    1. aluminum sulfide                                            b.   ammonium oxalate

  

  1. A factory makes gift-boxes that contain two pillows and one gold brick. The brick has a mass of 20 kg and each pillow has a mass of 1.0 kg.
    1. What is the mass percent of the pillows in each gift-box?
    2. What is the mass percent of the gold brick in the each gift-box?

 

  1. A truck of gift-boxes, each containing two light pillows and one heavy gold brick, can be used to represent a pure substance, water, formed of 2 mol of a light element, like hydrogen, and of 1 mol of a heavy element, like oxygen.
    1. What is the mass percent of hydrogen in 1 mol of water?
    2. What is the mass percent of oxygen in 1 mol of water?

 

  1. Would the mass percent of hydrogen and oxygen vary if there were 25 mol of water? Explain.