An athlete takes 15 breaths per minute at room temperature. The air inhaled in each breath is 245 ml which contains 21% oxygen by volume, while exhaled air contains 11% oxygen by volume. Assuming that

Question

An athlete takes 15 breaths per minute at room temperature. The air inhaled in each breath is 245 ml which contains 21% oxygen by volume, while exhaled air contains 11% oxygen by volume. Assuming that all the oxygen consumed is used for converting glucose into carbon dioxide and water, how much heat is produced (in kJ) in the body in one hour? Body temperature is 310 K and enthalpy of combustion of glucose is -2800 kJ/mol at 310 K.

TestHub · Accepted Answer

O 2 consumed per breath = (21% - 11%) × 245 = 24.5 ml at 298 K (room temperature; for glucose RQ = 1, so total gas moles are unchanged). Per hour: 24.5 × 900 = 22050 ml = 22.05 l, i.e. n O2 = 22.05/0.0821 × 298 = 0.901 mol. C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O, so n glucose = 0.901/6 = 0.1502 mol and heat = 0.1502 × 2800 = 420.6 ≈ 421 kJ. Answer: 0421.

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