MCQ
If the heat of formation of $C{O_2}$ is$ - 393\,kJ$. The amount of heat evolved in the formation of $0.156 \,kg $ of $C{O_2}$ is.....$kJ$
- A$ - 1357.9$
- B$ - 1275.9$
- ✓$ - 1572$
- D$ - 1165.5$
✓
Answer
Correct option: C.
$ - 1572$
(c)Heat of formation of a substance is the heat exchanged when one mole of that substance is formed by its constituent elements.
Heat evolved when $1 $ mole $(44\,g)\,C{O_2}$ is formed $ = 393\,kJ$
$\therefore $ Heat evolved when $0.156\,Kg\,(156\,g)$ is formed $ = \frac{{393 \times 156}}{{44}}$
$\therefore $ $\Delta H$ for the process $ = 1572\,kJ$$ = - 1572.0\,kJ$
Heat evolved when $1 $ mole $(44\,g)\,C{O_2}$ is formed $ = 393\,kJ$
$\therefore $ Heat evolved when $0.156\,Kg\,(156\,g)$ is formed $ = \frac{{393 \times 156}}{{44}}$
$\therefore $ $\Delta H$ for the process $ = 1572\,kJ$$ = - 1572.0\,kJ$
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