which statement about δhf is true? it is positive when the bonds of the product store more energy than those…
which statement about δhf is true? it is positive when the bonds of the product store more energy than those of the reactants. it is zero for any pure substance in its standard state. it is negative when a compound forms from elements in their standard states. it is zero for any compound that is in the liquid state.
Answer
Brief Explanations:
- Enthalpy of formation ($\Delta H_f$): The enthalpy change when one - mole of a compound is formed from its constituent elements in their standard states.
- If the bonds of the product store more energy than those of the reactants, energy is absorbed during the formation of the product. So, $\Delta H_f$ is positive.
- $\Delta H_f$ is zero for an element in its standard state, not for any pure substance. For example, a pure compound has a non - zero $\Delta H_f$.
- $\Delta H_f$ can be positive or negative when a compound forms from elements in their standard states. It depends on the nature of the compound.
- $\Delta H_f$ is not zero for any compound in the liquid state. Compounds in the liquid state have non - zero formation enthalpies depending on their composition and the elements from which they are formed.
Answer:
It is positive when the bonds of the product store more energy than those of the reactants.