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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 much heat (in MJ) is evolved per day ? $Δ H_{com}$ of sucrose is $- 6000 kJ mol^{- 1}$ .

Answer:

9.00

Solution:

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

O₂ consumed = $8856 \times 5% = 442.8$ L

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

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

Moles of sucrose burnt = $\frac{18}{12} = 1.5$ mol

Heat evolved = $1.5 \times 6000 = 9000 k J = 9 M J$

Stream:JEESubject:ChemistryTopic:ThermochemistrySubtopic:Enthalpy of Combustion

⏱ 2mℹ️ Source: QB

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