Endothermic Reaction — Definition, Formula, Properties & Uses | AllChemicals | AllChemicals

Q: What is the formula for Endothermic Reaction?

The formula or notation for Endothermic Reaction is: ΔH > 0 (heat absorbed); H_products > H_reactants

Formula / Notation	ΔH > 0 (heat absorbed); H_products > H_reactants
Also Known As	Heat-absorbing reaction, endothermal reaction, endergonic (for free energy)

What is Endothermic Reaction?

A chemical reaction that absorbs heat energy from the surroundings, causing the temperature of the surroundings to decrease. The enthalpy change (ΔH) is positive. Examples include dissolving ammonium nitrate in water and photosynthesis.

Formula & Notation

ΔH > 0 (heat absorbed); H_products > H_reactants

Other Names / Synonyms: Heat-absorbing reaction, endothermal reaction, endergonic (for free energy)

Properties & Characteristics

An endothermic reaction is one in which energy (usually as heat) is absorbed from the surroundings, so the system's enthalpy increases (ΔH > 0). The reactants have lower enthalpy than the products. Endothermic reactions make the surroundings cool. Examples: thermal decomposition of calcium carbonate (CaCO₃ → CaO + CO₂, ΔH = +178 kJ/mol), dissolving ammonium nitrate (ΔH > 0), photosynthesis.

Uses & Applications

Endothermic reactions are used in instant cold packs (NH₄NO₃ dissolving in water), endothermic shock absorbers, endothermic smelting operations (reduction of metal oxides), and in industrial cracking of hydrocarbons (steam cracking of naphtha to ethylene).

Safety Information

Endothermic reactions can cool reaction mixtures significantly, which can affect reactant solubility and potentially cause product precipitation. Heat-consuming reactions may need continuous energy input to maintain adequate rates. Some endothermic reactions (photochemical) proceed only under irradiation conditions.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Endothermic Reaction

Formula ΔH > 0 (heat absorbed); H_products > H_reactants

Index All "E" terms

Synonyms Heat-absorbing reaction, endothermal reaction, endergonic (for free energy)

Frequently Asked Questions

What is Endothermic Reaction?

A chemical reaction that absorbs heat energy from the surroundings, causing the temperature of the surroundings to decrease. The enthalpy change (ΔH) is positive. Examples include dissolving ammonium nitrate in water and photosynthesis.

What is Endothermic Reaction used for?

Is Endothermic Reaction hazardous?

What is the formula for Endothermic Reaction?

More "E" Terms

Effective Collisions Effective Collisions E ≥ Ea (activation energy required) Effective Molality m_eff = i × m (van't Hoff factor) Effective Nuclear Charge Z_eff = Z − σ (Slater's rules) Efflorescence Hydrated salt losing water in air: M·nH₂O(s) → M·(n-x)H₂O(s) + xH₂O(g) Einsteinium Es Electrical Conductivity κ = 1/ρ; Λm = κ/c Electrochemical Cell Galvanic cell: ΔG = −nFE_cell; Electrolytic cell: ΔG = +nFE_applied Electrochemical Series Arranged by E° (standard reduction potential); SHE: E° = 0.00 V Electrochemistry E° cell = E° cathode − E° anode | ΔG° = −nFE° Electrochemistry Electrode

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