Experiment 18 Calorimetry and Combustion PDF

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Chem 106 Lab report 18, burning food, where are my carbs? Calorimetry and combustion...

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Calorimetry and Combustion Introduction In experiment 18, we will verify the validity of the energy content of the various snacks by the use of the bomb calorimeter. In part 1, we will determine our H of the reaction or also called calorimeter constant, using 3.00g of glucose and net ionic equation. In part 2, we will compare the label information on energy content with the calculated energy content. Materials: 1. Laboratory manual 2. Calculator Observational and Experimental Part 1: 1) Net ionic equation C6 H 12 O6 ( s ) +6 O 2 ( g ) → 6 C O 2+ 6 H 2 O(g) Hrxn=nHpr-nHr (tabulated) Hrxn= (6*-393.5)+(6*-242)-(-1275)=-2538kJ/mol 2) 3g of C6H12O6/1224=0.01665 mol of C6H12O6 2538*0.01665=42.26kJ 42.26kj=ccal x(29.2-24.9) T=4.3 42.26kJ= Ccal*4.3=9.83kJ/C Part 2: q system=q mct=-q surrounding comb=q cal=Ccalt E cont=q comb (m) Q calc=CT Q calc= (4.8*9.83)=47.18kJ Q comb=47.18kj E content= -47.18kj/2.41=19.57kJ/g 19.57kJ/g*(1cal/4.184kJ)*(28.35g/10z)=132.63 cal/oz

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%error= (label-actual)/label= (160-132.63)/160=0.28% Food Sample

Mass (g)

Initial T (C)

Oreo cookie 2.41 26.12 Microwave 2.29 25.76 popcorn Crunchy Cheetos 2.21 25.13 Beef jerky 2.23 25.89 Oil-roasted, salted 2.45 25.64 peanuts Graph 1.a energy content of snacks provided.

Final T (C)

Energy Content Listed on Label

30.92 29.95

160 cal per serving (34g) 130 cal per serving (30g)

30.49 29.54 31.79

160 cal per serving (1oz) 80 cal per serving (1oz) 170 cal per serving (1oz)

T (C)

q cal

q comb

E content kJ/g

4.80

47.18kJ

-47.18kJ

4.19 41.18kJ -41.18kJ 5.36 52.69kJ -52.69kJ 3.65 35.88kJ -35.88kJ 6.15 60.45kJ -60.45kJ Graph 1.b energy content of snacks calculated.

%error

19.57kJ/g

E content cal/oz 132.63 cal/oz

0.28%

17.99kJ 23.84kJ/g 16.09kJ/g 24.68kJ/g

121.87 cal/oz 161.54 cal/oz 109.02cal/oz 167.20 cal/oz

0.63% 0.96% 36.28% 1.65%

Energy content from highest to lowest: 1. 2. 3. 4. 5.

Beef jerky Microwave popcorn Oreo cookies Crunchy Cheetos Oil-roasted peanuts

Section 5) Highest amount of measured and calculated calories belongs to oil-roasted peanuts. This can be tied to the fact that this snack is oil roasted, and fats have higher caloric amount than carbohydrates and proteins.

Discussion and Conclusion In this laboratory experiment, we have proved that fat contents have higher caloric value than carbohydrates and proteins by the use of calorimetry. We have also gained a knowledge that food being metabolized is converted to energy, and the amount of energy is directly proportional to the properties of our food, such as fats, carbohydrates, and proteins. We have also calculated exact amount of energy

3 released by using calorimetry, and the calorimetry constant determined by glucose. This lab has provided an important insight how our food can influence the outcome on our energy.

References

Smeureanu, G., Geggier, S. General Chemistry Laboratory, New York City, Hunter College, Publishing 2020, p. 139-144 Focus questions:

1. The amount energy released from food, is the amount that each food caries depending what types of macromolecules it is composed from. Macromolecules such as fats, carbohydrates, or proteins. When food is burned, all the energy available is released. 2. The caloric content is determined by energy released from food when it’s burned. We can determine those values by the combustion reaction using calorimeter. Post-lab assessment questions: 1. Highest amount of measured and calculated calories belongs to oil-roasted peanuts. This can be tied to the fact that this snack is oil roasted, and fats have higher caloric amount than carbohydrates and proteins. 2. Fat is considered to store the most energy out of the three recognized “macros” in our diet. We can compare the 9 dietic calories per gram to 4 dietic calories per gram of protein and carbohydrates. It is more than double amount than proteins and carbohydrates. 3. The reason why we should calculate calories per gram rather than calories burned is that we can make direct comparisons to other samples. “Calories burned” is very vague measurement and can easily be misleading. 4. 3.55g/342.2965(g/mol)=0.01mol (27.74-23.42)*4.7=20.304kJ -20.304kJ/0.01=-2030kj/mol...