Question

A human requires about 2000 kcal per day. Suppose that all of that energy comes from pure sugar, which contains 4.0 kcal/g.

A) How many grams of sugar would a person need in a day? Approximately how much would they consume a year?

B) Glucose has the chemical formula C6H12O6. If a molecule of glucose is broken down into pure CO2 and water, how many molecules of each would it make?

C) Carbon has a molecular weight of 12, hydrogen of 1, and oxygen of 16. What fraction of the mass of sugar molecule would be released as CO2?

D) With this diet of pure sugar, how much CO2 would a person release in a year?

E) An urban resident of the Baltic region produces about 10 kg of carbon dioxide per day. How does this compare with the amount their body produces just from living?

Answer 1

A) 5% of total calorie consumption should be sugar consumption
1 gm of sugar has 4kcal
? gm of sugar has 2000kcal
With a diet of pure sugar it should be 500 gms (2000/4)
otherwise, 5% of (2000/4) i.e) 500 gm which is = 0.05*500 = 25 gms of sugar per day
In a year we have 365 days,
with the diet of pure sugar it should be = 2000kcal * 365 = 730000 kcal
otherwise, 25 gms * 365 = 9125 gms of sugar in a year = 9125gm*4kcal/gm = 36500kcal in a year

B) 6 CO₂ and 6 H₂O molecules are required.

C) mass of C₆H₁₂O₆ = 6*12 + 12*1 + 16*6 = 180 gm/mol
mass of CO₂ = ( 12*1 + 2*16) = 44 gm/mol
mass fraction of sugar molecule released as CO₂ = 44 / 180 = 0.2444

D) 0.2444*44 gm/mol * 6 mol of CO₂ = 64.5216 gms of CO₂ is produced for 1 gm of sugar
1 gm of sugar gives 64.5216 gms of CO₂
500 gms of sugar will give ? gms of CO₂
32260.8 gms of CO₂ or 32.2608 Kg of CO₂ is produced in a day
For a year with pure-sugar diet = 32.2608 kg * 365 = 11775.192 Kg of CO₂ will be released by a person.