Question

When the reactants and products are at their standard states, the change in enthalpy accompanying the formation of 1 mole of a substance from the constituent elements is termed as:

• A. The standard heat of reaction
• B. The standard heat of formation
• C. The standard heat of combustion
• D. The standard heat of accumulation

Hint:

The standard heat of formation is a fundamental concept in thermodynamics, often used to calculate the enthalpy change for chemical reactions using Hess's law.

Answer 1

The Correct Option is B

Step 1: Define standard heat of formation. 
The standard heat of formation is the enthalpy change when one mole of a substance is formed from its elements in their standard states at 1 bar pressure and 298 K temperature. 
Step 2: Compare with other terms. 
Standard heat of reaction refers to the heat change during any reaction under standard conditions.
Standard heat of combustion refers to the heat change when one mole of a substance reacts completely with oxygen under standard conditions.
Standard heat of accumulation is not a commonly used term in thermodynamics.
Step 3: Conclusion. The correct term for the enthalpy change accompanying the formation of 1 mole of a substance from its constituent elements is the standard heat of formation. 
Final Answer: The change in enthalpy accompanying the formation of 1 mole of a substance from the constituent elements is termed the standard heat of formation.