1. What is Delta H in Chemistry?

Delta H (ΔH) represents the change in enthalpy of a system at constant pressure. It is a measure of the heat energy absorbed or released during a chemical reaction or physical process.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( q_p \) — Heat at constant pressure (Joules)
• \( n \) — Amount of substance (moles)

Explanation: This equation calculates the enthalpy change per mole of substance when heat is transferred at constant pressure conditions.

3. Importance of Delta H Calculation

Details: Calculating ΔH is essential for understanding the thermodynamics of chemical reactions, determining whether reactions are exothermic or endothermic, and predicting reaction spontaneity.

4. Using the Calculator

Tips: Enter the heat transferred at constant pressure in Joules and the amount of substance in moles. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What does a positive ΔH value indicate?
A: A positive ΔH indicates an endothermic reaction where heat is absorbed from the surroundings.

Q2: What does a negative ΔH value indicate?
A: A negative ΔH indicates an exothermic reaction where heat is released to the surroundings.

Q3: Why is constant pressure important for this calculation?
A: At constant pressure, the heat transfer (q_p) equals the change in enthalpy (ΔH), making this relationship valid.

Q4: What are typical units for ΔH?
A: ΔH is typically expressed in J/mol or kJ/mol, representing energy change per mole of substance.

Q5: How does ΔH relate to Gibbs free energy?
A: ΔH is one component of the Gibbs free energy equation (ΔG = ΔH - TΔS), which determines reaction spontaneity.