Which of the following reactions defines Delt | vedclass

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Question

(B) The standard enthalpy of formation $(\Delta H_f^o)$ is defined as the enthalpy change when $1 \ mol$ of a substance is formed from its constituent

Vedclass · Accepted Answer

$\frac{1}{2} H_{2(g)} + \frac{1}{2} F_{2(g)} 	o HF_{(g)}$

Vedclass · Answer

(B) The standard enthalpy of formation $(\Delta H_f^o)$ is defined as the enthalpy change when $1 \ mol$ of a substance is formed from its constituent elements in their most stable standard states.In option $(B)$,$1 \ mol$ of $HF_{(g)}$ is formed from $H_{2(g)}$ and $F_{2(g)}$,which are the standard states of hydrogen and fluorine.Option $(A)$ is incorrect because diamond is not the most stable standard state of carbon (graphite is).Option $(C)$ is incorrect because it forms $2 \ mol$ of $NH_3$.Option $(D)$ is incorrect because $CO$ is a compound,not an element.Thus,$(B)$ is the correct answer.

Which of the following reactions defines $\Delta H_f^o$?

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