What is the standard enthalpy change of formation for an element in its standard
Practice Questions
Q1
What is the standard enthalpy change of formation for an element in its standard state?
0 kJ/mol
100 kJ/mol
298 kJ/mol
1 kJ/mol
Questions & Step-by-Step Solutions
What is the standard enthalpy change of formation for an element in its standard state?
Step 1: Understand what 'standard enthalpy change of formation' means. It refers to the heat change when one mole of a compound is formed from its elements in their standard states.
Step 2: Recognize what 'standard state' means. The standard state of an element is its most stable form at 1 atmosphere of pressure and a specified temperature (usually 25 degrees Celsius).
Step 3: Identify that elements in their standard state do not require any energy to form themselves. For example, oxygen gas (O2) is in its standard state as a diatomic molecule.
Step 4: Conclude that since no energy is needed to form an element from itself, the standard enthalpy change of formation for an element in its standard state is defined as 0 kJ/mol.
