Q58 / 180 · NEET 2015 (Phase 2) · Chemistry

The heat of combustion of carbon to $C O_{2}$ is $- 393.5 kJ / mol$ . The heat released upon the formation of $35.2 g$ of $C O_{2}$ from carbon and oxygen gas is

Correct answer
A
$- 315 k J$
B
$+ 315 k J$
C
$- 630 k J$
D
$- 3.15 k J$

Solution

Formation of

C O_{2}

from carbon and dioxygen gas can be represented as

C (s) + O_{2 (g)} \to C O_{2 (g)}; ∆_{f} H = - 393.5 k J m o l^{- 1}

(

1 mole = 44 g

)

The heat released on formation of

44 g

C O_{2}

= - 393.5 k J m o l^{- 1}

= \frac{- 393.5 k J m o l^{- 1}}{44 g} \times 35.2 g

= - 315 k J

Hence, the correct answer is option: 'A'.

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