EXPERIMENT 15: Calorimetry Real world application
You have been asked to experimentally determine the Calorie values of various desserts. You realize that a combustion reaction is analogous to the digestive reaction occurring during metabolism and the amount of energy released from combustion will tell us how much nutritional energy we can expect from the food. You then need to apply the principles of calorimetry to measu re the energy released by the desserts upon combustion. After some research, you discover that calorimetry of combustion reactions is performed in an instrument called a bomb calorimeter, which is shown below. The name ĂąÂÂbombù refers to the innerchamber of the calorimeter that can withstand great increases in pressure.
You need to convince your advisor to buy this instrument and then discuss how you will measure the calorie values of the assigned desserts, like cotton candy.
1.First, you are asked to justify your use of the expensive bomb calorimeter to measure the heat released by combustion. Give at least one reason why the cheaper coffee cup calorimeter will not work for this measurement.
2.The main ingredient of the desserts you will be studying is sugar or sucrose. Look up the MSDS for sucrose. What kind of fire extinguisher should you have/use if the fire(combustion reaction) gets out of hand?
3.Now that youĂąÂÂve justified the instrument to your boss and are ready to work safely, you investigate your options more closely and notice that most ĂąÂÂbombù inner chambers are made of stainless steel. Stainless steel is not a good insulator but is instead a good conductor of heat. Why is the ĂąÂÂbombù made of this type of material and not an insulator?
4. Finally, you have purchased the bomb calorimeter and are ready toperform the measurement of cotton candy. You look into the inner chamber and the cotton candy seems to be completely
gone. Where did it go? Refer to the balanced combustion reaction for cotton candy, which is mostly sucrose (C12H22O11), in your answer.
5.Your cotton candy experiment was run in a calorimeter with 425 mL of water that started at 24.0 degree C. After combusting 2.00 g of cotton candy, the temperature of the water was measured at 41.3 degree C. How many Calories of energy will be released from metabolizing one serving of cotton candy (60.0 g)? Remember 1 Calorie=4184 J. Assume all heat from combustion transferred with 100% efficiency to the water?
