Question

Which of the following is a correct statement of Hess’s Law?


The enthalpy change for the conversion of reactants to products must be determined by examining the pathway.

The enthalpy change for the conversion of reactants to products is dependent on the steps of the reaction.

When a reaction proceeds from reactants to products, the change in enthalpy is the same whether the reaction pathway involves one step or several.

When a reaction proceeds from reactants to products, the change in enthalpy can be determined.

The standard enthalpy of formation for a compound is the change in enthalpy that occurs when which of the following happens?


1 mol of a substance is formed from its elements in their standard states.

An element changes into its standard state.

1 mol of a substance is formed from its ions

A substance is formed from 1 mol of its elements in standard state

Answer 1

1. When a reaction proceeds from reactants to products, the change in enthalpy is the same whether the reaction pathway involves one step or several.

2. 1 mol of a substance is formed from its elements in their standard states.