Hydration — Definition, Formula, Properties & Uses | AllChemicals | AllChemicals

Q: What is the formula for Hydration?

The formula or notation for Hydration is: ΔGhyd = −ΔHhyd (negative, exothermic) | Net: ΔHsol = ΔHlattice + ΔHhyd

Formula / Notation	ΔGhyd = −ΔHhyd (negative, exothermic) \| Net: ΔHsol = ΔHlattice + ΔHhyd
Also Known As	Solvation in water, Aquation, Hydration shell formation

What is Hydration?

The process by which water molecules surround and interact with dissolved ions or molecules (solvation in water). The release of energy during hydration (hydration enthalpy) helps overcome lattice energy when ionic compounds dissolve. Also refers to adding water across a double bond.

Formula & Notation

ΔGhyd = −ΔHhyd (negative, exothermic) | Net: ΔHsol = ΔHlattice + ΔHhyd

Other Names / Synonyms: Solvation in water, Aquation, Hydration shell formation

Properties & Characteristics

Hydration enthalpy: energy released when 1 mol gaseous ions are surrounded by water. Always exothermic. Values: Li⁺ = −519, Na⁺ = −406, K⁺ = −322, Mg²⁺ = −1922, Al³⁺ = −4690 kJ/mol. Larger charge and smaller radius → more negative hydration enthalpy. Hydration number (water molecules in first shell): Na⁺ ≈ 6, Mg²⁺ ≈ 6, Al³⁺ ≈ 6. Drives dissolution when |ΔHhyd| > ΔHlattice.

Uses & Applications

Explains why ionic compounds dissolve in water. Salt dissolution in seawater and body fluids. Ion transport in biological systems. Kidney function (ion excretion). Dialysis in renal failure. Electrolyte solutions in batteries. Ion exchange chromatography. Water softening process (Ca²⁺ and Mg²⁺ hydration).

Safety Information

Concentrated sulfuric acid has extreme hydration enthalpy — adding water to concentrated H₂SO₄ releases so much heat it can cause violent spattering. Always add acid to water slowly. Anhydrous salts (CaCl₂, MgSO₄) release heat on hydration — handle carefully to avoid burns.

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

Key Facts

Term Hydration

Formula ΔGhyd = −ΔHhyd (negative, exothermic) | Net: ΔHsol = ΔHlattice + ΔHhyd

Index All "H" terms

Synonyms Solvation in water, Aquation, Hydration shell formation

Frequently Asked Questions

What is Hydration?

The process by which water molecules surround and interact with dissolved ions or molecules (solvation in water). The release of energy during hydration (hydration enthalpy) helps overcome lattice energy when ionic compounds dissolve. Also refers to adding water across a double bond.

What is Hydration used for?

Is Hydration hazardous?

What is the formula for Hydration?

More "H" Terms

Haber Process N₂ + 3H₂ ⇌ 2NH₃ | ΔH = −92 kJ/mol Hafnium Hf Half Cell Half Life Half-Cell E = E° − (RT/nF)lnQ Half-Life A(t) = A₀e^(−λt); t½ = ln2/λ Half-Reaction Halide X⁻ (e.g., F⁻, Cl⁻, Br⁻, I⁻) Halogen F₂, Cl₂, Br₂, I₂, At; Group 17; ns²np⁵ valence configuration Halogenation C-X + Cl₂/Br₂ (hv or AlCl₃) → C-X(halogen); EAS or radical pathway Halogens Hard Acid Hard acid: small, highly charged, low polarisability (e.g., H⁺, Mg²⁺, Al³⁺)

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