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ChemistryThermochemistryEnthalpy of CombustionMedium2 minQB

ChemistryMediumnumerical

Passage / Comprehension

A person takes 15 breaths per minute . The volume of air inhaled in each breath is 410 ml and contains 21% of oxygen by volume . The exhaled air contains 16% of oxygen by volume. Take temperature & pressure to be 300 K & 1atm respecitvely throughout the process. If all the oxygen is used only in the combustion of sucrose, ( $R = 0.082 L - atm / K - mol$ ).

How many gram of sucrose $(C_{12} H_{22} O_{11})$ is burnt in the body per day ?

Answer:

513.00

Solution:

Air inhaled per day = $15 \times 410 \times 60 \times 24 = 8856000$ mL = $8856$ L

O₂ consumed = $8856 \times (21 - 16) % = 442.8$ L

Using $P V = n RT$ :

$n (O_{2}) = \frac{P V}{RT} = \frac{1 \times 442.8}{0.082 \times 300} = 18 m o l$

Combustion:

$C_{12} H_{22} O_{11} + 12 O_{2} \to 12 C O_{2} + 11 H_{2} O$

1 mol sucrose consumes 12 mol O₂, so sucrose burnt = $\frac{18}{12} = 1.5$ mol

Mass of sucrose = $1.5 \times 342 = 513$ g

Stream:JEESubject:ChemistryTopic:ThermochemistrySubtopic:Enthalpy of Combustion

⏱ 2mℹ️ Source: QB

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