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What are the two conditions for imbibition to occur?

GeneralClass 12AllAnswered 27 Mar 2026
Answer

Imbibition is the passive absorption of water by hydrophilic colloids, causing them to swell. Two essential conditions are:

Condition

Explanation

1. Water Potential Gradient

There must exist a water potential gradient between the imbibant (solid substance) and the imbibate (liquid, usually water). Water moves from higher Ψ<sub>w</sub> (liquid) to lower Ψ<sub>w</sub> (solid).

2. Affinity Between Imbibant and Imbibate

The solid imbibant must have a strong chemical affinity for water. Hydrophilic substances like cellulose, proteins, starch, and agar have hydroxyl (-OH) or amino (-NH₂) groups that form hydrogen bonds with water molecules.

Practical Examples:

  • Seed germination: Dry seeds imbibe water, causing seed coat rupture
  • Swelling of wooden doors during monsoon
  • Prehistoric rock splitting using wet wooden wedges

Imbibition Pressure: The pressure developed during imbibition can be tremendous (up to 1000 atmospheres), sufficient to break rocks.

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General · Class 12