1. What is an Endothermic Reaction?

An endothermic reaction is a chemical reaction that absorbs heat from its surroundings, resulting in a positive enthalpy change (ΔH > 0). These reactions typically feel cold to the touch as they take in thermal energy.

2. How Does the Calculator Work?

The calculator uses the endothermic reaction formula:

Where:

• \( \Delta H \) — Enthalpy change (J)
• Heat Absorbed — Amount of thermal energy absorbed by the reaction (J)

Explanation: For endothermic reactions, the enthalpy change (ΔH) equals the amount of heat absorbed by the system from the surroundings.

3. Importance of ΔH Calculation

Details: Calculating enthalpy change is crucial for understanding reaction thermodynamics, predicting whether reactions will occur spontaneously, and designing energy-efficient chemical processes.

4. Using the Calculator

Tips: Enter the heat absorbed value in joules (J). The value must be positive as endothermic reactions absorb energy from their surroundings.

5. Frequently Asked Questions (FAQ)

Q1: What distinguishes endothermic from exothermic reactions?
A: Endothermic reactions absorb heat (ΔH > 0), while exothermic reactions release heat (ΔH < 0) to their surroundings.

Q2: What are some common examples of endothermic reactions?
A: Photosynthesis, evaporation of water, thermal decomposition, and dissolving ammonium nitrate in water are common endothermic processes.

Q3: How is heat absorption measured experimentally?
A: Calorimetry is the primary experimental method, where temperature changes are measured in an insulated container to determine heat flow.

Q4: Can endothermic reactions occur spontaneously?
A: Yes, if the increase in entropy is sufficient to overcome the positive enthalpy change, as determined by the Gibbs free energy equation (ΔG = ΔH - TΔS).

Q5: Why do endothermic reactions feel cold?
A: They absorb thermal energy from their surroundings, including from your skin, creating a cooling sensation.