Experiment 1: Determining the Energy in Food You will determine the amount of ca

Question

Experiment 1: Determining the Energy in Food

You will determine the amount of calories in a marshmallow and compare your results to the nutritional panel

Procedure

1. Obtain the mass of the marshmallow using the digital scale. Record this value

2. Measure 100 mL of room temperature water using the 100 mL beaker. Pour the water into the aluminum can. Then, place the thermometer in the can to measure the temperature of the water. Record this value.

3. Use a butter knife or scissors to carefully cut the marshmallow into four equal quarters.

4. Using either the top or bottom of your Petri dish, cover the dish in aluminum foil and then place the cut marshmallows into the dish so that the sides of the dish can contain the marshmallows

Note: The aluminum foil is used to create a nonflammable surface. Be sure to completely cover all edges and area of the Petri dish.

5. Place the Petri dish with cut marshmallows on a flat, nonflammable surface, ignite all four marshmallow pieces with the matches, and immediately hold the aluminum can full of water over the center of the flame.

Keep the bottom of the can close to the flame while ensuring that neither touch.

6. The flame may burn out before burning through the entire marshmallow. If this occurs, relight the marshmallow. Be sure that you do not let the flame touch the aluminum can when lighting the marshmallow again. Continue this process until the marshmallow is burnt completely.

7. Quickly measure the temperature of the water with the thermometer after the marshmallow has been burned completely. Do not touch the thermometer to the sides or bottom of the can. Record the temperature

A. Calculate the thermal energy in the burnt marshmallow using the equation, Q=mc?T. Show all work for full credit.

B. Convert your answer from Question A into Calories.

C. Calculate percent error between your results and the listed nutritional information (1 marshmallow is 23 Calories).

D. Why do you suppose there could be any differences?

E. What is the purpose of cutting the marshmallows into four quarters? How might the experimental results have changed if the marshmallow was burned in one piece?

f. Based on the design of the marshmallow experiment and on your percent error, would you have designed this experiment differently? Explain why or why not, and if applicable, how you would design it differently.

THE ROOM TEMPERATURE WATER IS 68 DEGREES F. OR 20 DEGREES C.

okay, it's not due until midnight tonight? will it be completed?

Explanation / Answer

A. Calculate the thermal energy in the burnt marshmallow using the equation, Q=mc?T. Show all work for full credit.

Let us assume a typical marshmallow weights 7.5g, in this experiment one marshmallow used?

Water used is 100ml = 100g

Initial temperature of water = 20 °C

Final temperature not given in the problem... i think you have to calculate by doing experiment

First calculate the temperature change ?T lets say final water temperature is 100°C = 100-20 = 80 °C

Second use equation, Q=mc?T ; m- is mass marshmallow weights 7.5g + 100g water = 107.5g

Remember that c = 4.2 J/g°C for liquids (unless you are told otherwise)

Then Q = 107.5 x 4.2 x 80 = 36120 Joules

B. Convert your answer from Question A into Calories.

We know that E(cal) = E(J) / 4.184

= 36120/4.184 = 8632 Calories

C. Calculate percent error between your results and the listed nutritional information (1 marshmallow is 23 Calories).

Based on final temperature this changes, percentage error calculated as if 23 calories is 100% for 8632 how much?

D. Why do you suppose there could be any differences?

Difference may be due to error in the marshmallow weight accuracy, if its not burnt completely, if heat energy not completely transferred to raise the water temeprature, error in temperature measurement so on so forth

E. What is the purpose of cutting the marshmallows into four quarters? How might the experimental results have changed if the marshmallow was burned in one piece?

purpose of cutting the marshmallows into four quarters is to burnt it completely in a single go. If burned in one peace it might not have burned completely, by repeated re igniting we creating error in rapid heating of water and detecting temeprature in single go, intermittant and disturbed heating does not raise temperature properly, inbetween water cools down and creates errors.

F. Based on the design of the marshmallow experiment and on your percent error, would you have designed this experiment differently? Explain why or why not, and if applicable, how you would design it differently.

Percent error is huge because of the design, i could have designed this experiment based on direct measurement of temperature raise by burning marshmallow in an instrument like bomb calorimeter or in a device which rapidly and accurately transfers heat energy to water. If the heat energy transfer is not done properly there could be failure and this experiment is hugely error prone hence i dont use this crude system and i use a little sophisticated instrument to measure the calories of marshmallow. I will design by burning the marshmallow in a closed system attached with a thermometer or thermo sensor which accurately measure the change in temperature so that my data parameters will be accurate to measure calorific value of marshmallow.

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