1. What is an Endothermic Reaction?

An endothermic reaction is a chemical reaction that absorbs energy from its surroundings, typically in the form of heat. This is indicated by a positive change in enthalpy (ΔH > 0).

2. How Does the Calculator Work?

The calculator uses the enthalpy change (ΔH) principle:

Where:

• \( \Delta H \) — Change in enthalpy (kJ/mol)
• Positive ΔH indicates endothermic reaction
• Negative ΔH indicates exothermic reaction
• Zero ΔH indicates thermoneutral reaction

Explanation: The sign of ΔH determines whether energy is absorbed (endothermic) or released (exothermic) during the reaction.

3. Importance of ΔH Calculation

Details: Knowing whether a reaction is endothermic or exothermic is crucial for understanding reaction thermodynamics, predicting reaction feasibility, and designing chemical processes.

4. Using the Calculator

Tips: Simply enter the ΔH value in kJ/mol. The calculator will determine whether the reaction is endothermic, exothermic, or thermoneutral based on the sign of ΔH.

5. Frequently Asked Questions (FAQ)

Q1: What are common examples of endothermic reactions?
A: Photosynthesis, thermal decomposition, and the reaction between barium hydroxide and ammonium chloride are classic examples.

Q2: How is ΔH measured experimentally?
A: ΔH is typically measured using calorimetry techniques that track heat flow during a reaction.

Q3: Can endothermic reactions occur spontaneously?
A: Yes, if the increase in entropy (ΔS) is large enough to compensate for the positive ΔH (ΔG = ΔH - TΔS < 0).

Q4: What's the difference between ΔH and ΔG?
A: ΔH measures enthalpy change (heat content), while ΔG measures Gibbs free energy change (spontaneity).

Q5: Why do endothermic reactions feel cold?
A: They absorb heat from their surroundings, causing the temperature of the environment to decrease.