What is imbibition?
The absorption of water by the solid particles of an adsorbent without forming a solution is known as imbibition.
It is a special type of diffusion in which water movement occurs due to difference in water molecule concentration between imbibate (water) and the imbibant (solid colloid substances or adsorbent).
The solid substance which absorbs water and swells up is known as imbibant.
The liquid or water which is imbibed by the imbibant is known as imbibate.
The most important substance of imbibition is the adsorbent. Therefore, the imbibition of water increases the volume of the imbibant due to the Imbibitional Pressure (IP) is created in the imbibant.
Conditions necessary for imbibition:
  • This process occurs only when there a concentration gradient (water potential gradient) is formed between the adsorbent and the liquid imbibed.
  • There should be some affinity between imbibant and imbibed liquid.
Mass % of water imbibed:
When an adsorbent is placed in water it increases enormously in volume. The mass percentage of the water which is imbibed is calculated by using the following formula.
Massof water imbibed = massofwaterabsorbedbytheimbibantinitialmassoftheimbibant×100
An experiment about imbibition:
To determine the mass percentage of water imbibed by raisins.
Materials required:
Raisins, \(50 mL \)beaker, thermometer,  physical balance with weight box, blotting paper and a pair of foreceps.
  • Take about \(20\) dry and clean raisins, which are approximately the same size.
  • Note down their mass (\(m1\)) with the help of a physical balance.
  • Take water in a beaker and note down its temperature (\(θ\)).
  • Place the raisins in the beaker for about an hour (note that the raisins are completely swollen within an hour).
  • Remove the swollen raisins from the beaker with the help of forceps and gently roll
    them on a blotting paper to remove the water sticking to their surface.
  • Weigh the swollen raisins to find their final mass (\(m2\)).
Observations and calculations:
  • Temperature of water, θ = __________ °C = __________ K
  • Initial mass of the twenty dry raisins, m1 = __________ g
  • Final mass of the swollen raisins, m2 = __________ g
  • Mass of the water absorbed by the raisins, (m2 - m1) = __________ g
Massof water imbibed = massofwaterabsorbedbytheimbibantinitialmassoftheimbibant×100
Mass % of water imbibed=m2m1m1×100
= __________.
Results and discussion:
The mass percent of water absorbed by the raisins at temperature __________ K is __________ %. Analyse the reasons of water imbibed by the raisins.
Imbibition by raisins