which of the following statements about enthalpy is true? enthalpy of a substance can be measured directly…

which of the following statements about enthalpy is true? enthalpy of a substance can be measured directly. enthalpy is the gradual decline into disorder. enthalpy is a measure of the change in pressure of a system. a chemical process must occur and then changes between the state of the reactants and the state of the products can be determined.

which of the following statements about enthalpy is true? enthalpy of a substance can be measured directly. enthalpy is the gradual decline into disorder. enthalpy is a measure of the change in pressure of a system. a chemical process must occur and then changes between the state of the reactants and the state of the products can be determined.

Answer

Brief Explanations:

Enthalpy ($H$) is a state - function. The absolute value of enthalpy of a substance cannot be measured directly. Entropy is the gradual decline into disorder, not enthalpy. Enthalpy is not a measure of change in pressure. Enthalpy change ($\Delta H$) is determined by the difference between the enthalpy of products and reactants in a chemical process.

Answer:

A chemical process must occur and then changes between the state of the reactants and the state of the products can be determined.