Lab 3 Caloric Content of food

Topics: Heat, Energy, Thermodynamics Pages: 5 (613 words) Published: November 16, 2014
Ocean County College
Department of Chemistry
Lab 3 Caloric Content of Food
Submitted by
Juan C. Delgado Román
Student # 0439722

                                          Date Submitted:  October 26, 2014
Date Performed:  October 25, 2015
Lab Section: Chem-180         
Course Instructor:  Lea Stage
                                                       Purpose
On this experiment we will learn how measure the energy content of 3 food items and become familiar with energy units: joules, and calories.  Procedure
For this laboratory exercise we use the following materials: Lighter, aluminum tray, metal fork, a piece of marshmallow, a walnut, and a potato chip, water, 100 ml beaker, burner stand, burner, digital scale, test tube clamp holder, thermometer. I first weighted empty beaker, then beaker filled with 50ml of water. Recorded each weight and the difference was the water mass. I placed the burner stand inside aluminum tray, then the beaker filled with water on top of burner stand. Measured the initial water temperature. I left the thermometer inside the beaker to measure water heat later. I started with a marshmallow. I weighted alone first the marshmallow and the fork. Later weighted both together. I subtracted the total weight of fork + marshmallow to obtain the food item weight. I lit the marshmallow and once on fire, I placed it under the beaker and waited until burned completely. Then measured the final water temperature, weighted fork with remaining of the burnt marshmallow. I repeated the same steps with a piece of walnut and a potato chip. Each time I would use fresh water, clean, dry out and allow the equipment to cool down.

A.Marshmallow: 7g
Metal Fork: 44.9g
Together: 56.2g

B.Walnut: 1.7g
Clamp: 26.1g
Together: 27.9g

C.Potato chip: 1.8g
Clamp: 26.1g
Together: 27.9g

I calculated with each food item: the change in temperature, ∆t= t final – t initial, mass of water in beaker, the heat energy gained by water, Q= ∆*m*cp, given the specific heat capacity of water, 4.184J/g˚C and determine the heat energy per gram in joules/calories. Marshmallow: 86J/cal or 21 calories

Walnut: 3,298J/g or 788 calories
Potato chip: 1,811J/g or 433 calories

Observations and Results

Data Table 1: Food Item - Observations
Food Item Description:
Marshmallow
Walnut
Potato Chip
Mass of food & holder – initial
56.2g
27.9g
27.9g
Mass of food & holder – final
44.9g
26.2g
26.2g
Mass of food burnt
11.3g
1.7g
1.7g
Mass of beaker
62.7g
62.7g
62.7g
Mass of beaker & water
108.9g
108.9g
108.7g
Mass of water
46.2g
46.2g
46g
Water temp. – Initial
27˚C
26˚C
27˚C
Water temp. – Final
32˚C
55˚C
43˚C
Delta T (oC change)
5˚C
29˚C
16˚C
 

Conclusions
Summarize your conclusions and explain why or why not your experiment was successful.  This laboratory exercise showed how to measure the energy content of 3 common food samples that people eat, which was successful. We learned how to make and use made a small version of a calorimeter at home. We also used joules, SI, to measure energy. Whoever, given the food item of choice indicated, the use of a marshmallow, was difficult and I believe in my case did not give better result as it was difficult to burn evenly without extinguishing the fire more than 7 times in the process. I would have used 2 small (or the mini version) of marshmallow instead of the standard common size of it. Maybe it would have given better outcome in energy content by burning more evenly. The instructions did not specify what size of marshmallow to be used, neither gave the option to use other food items that a student could have at home without the need to spend money on a item I do not eat at all. I did enjoy the process and wish I had more suggestions of food items.

References & Pictures

1.     Timberlake & Timberlake (2014), Basic Chemistry. Los Angeles: Pearson...

References: & Pictures
1.     Timberlake & Timberlake (2014), Basic Chemistry. Los Angeles: Pearson
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