What is the standard enthalpy change of formation for a substance?
Practice Questions
Q1
What is the standard enthalpy change of formation for a substance?
The enthalpy change when one mole of a compound is formed from its elements in their standard states.
The enthalpy change when one mole of a substance is completely burned in oxygen.
The enthalpy change when one mole of a substance is dissolved in water.
The enthalpy change when one mole of a gas is compressed to a smaller volume.
Questions & Step-by-Step Solutions
What is the standard enthalpy change of formation for a substance?
Correct Answer: Standard enthalpy change of formation is the heat change when one mole of a compound is formed from its elements in their standard states.
Step 1: Understand that 'enthalpy' is a measure of energy in a system.
Step 2: Know that 'standard enthalpy change of formation' refers to a specific type of energy change.
Step 3: Recognize that this change occurs when one mole of a compound is created.
Step 4: Identify that the compound is formed from its basic building blocks, which are its elements.
Step 5: Ensure that these elements are in their 'standard states', meaning they are in their most stable form at a specific temperature and pressure (usually 1 atm and 25°C).
Step 6: Conclude that the standard enthalpy change of formation is the energy change associated with this process.
