The heat of formation is the change in enthal | vedclass

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(C) The enthalpy of formation $(\Delta H_f)$ is defined as the change in enthalpy when $1 \ mole$ of a substance is formed from its constituent elemen

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May be negative or positive

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(C) The enthalpy of formation $(\Delta H_f)$ is defined as the change in enthalpy when $1 \ mole$ of a substance is formed from its constituent elements in their standard states.Since the enthalpy of elements in their standard state is defined as zero,the enthalpy of formation of a compound depends on the energy released or absorbed during the bond formation process.Exothermic reactions result in a negative $\Delta H_f$,while endothermic reactions result in a positive $\Delta H_f$. Therefore,the heat of formation of compounds can be either negative or positive.

The heat of formation is the change in enthalpy accompanying the formation of a substance from its elements at $298 \ K$ and $1 \ atm$ pressure. Since the enthalpies of elements are taken to be zero,the heat of formation $(\Delta H_f)$ of compounds

Similar Questions

The enthalpy change $(\Delta H)$ for the process $N_2H_{4(g)} \to 2N_{(g)} + 4H_{(g)}$ is $1724 \ kJ \ mol^{-1}$. If the bond energy of $N-H$ bond in ammonia is $391 \ kJ \ mol^{-1}$,what is the bond energy of $N-N$ bond in $N_2H_4$ in $kJ \ mol^{-1}$?

At $1 \ bar$ and $298 \ K$,the standard molar enthalpy of formation of which substance is zero?

For which of the following reactions will the value of $\Delta H$ be positive?

The heat of neutralization of $HCl$ by $NaOH$ is $-57.3 \, kJ/mol$. If the heat of neutralization of $HCN$ by $NaOH$ is $-12.1 \, kJ/mol$,then the enthalpy of dissociation of $HCN$ is $...... \, kJ$.

The standard enthalpy of formation,$\Delta H^o_f$ $(298 \ K)$,of methanol is represented by which of the following chemical equations?

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