What happens to capillary rise when temperature rises?

Capillary rise is directly proportional to the surface tension and inversely proportional to the density as you can see in the formula…


h=4σ cosΘ/ρgD


When the temperature starts rising the surface tension decreases along with the density.

Initially the effect of decrease in the surface tension dominates and the capillary rise is smaller.

After a Certain point of time the effect of decrease in density dominates and capillary rise increases.

Hope this helps…

Explanation:
Capillarity is the phenomenon of a liquid rising or falling in a narrow tube or porous material due to the combination of adhesive and cohesive forces. The rise or fall of a liquid in capillarity is influenced by various factors, including temperature.

Effect of Temperature on Capillarity:
Temperature has a significant effect on the capillarity of liquid fluids. The relationship between capillarity and temperature can be explained as follows:

1. Decrease in Capillarity with Rise in Temperature:
- As the temperature increases, the cohesive forces between the liquid molecules decrease.
- Consequently, the surface tension of the liquid decreases with an increase in temperature.
- The decrease in surface tension results in a decrease in capillarity or the ability of the liquid to rise in a capillary tube.
- Therefore, as the temperature rises, the capillarity of liquid fluids decreases.

2. Reason for Decrease in Capillarity:
- The decrease in capillarity with temperature can be attributed to the decrease in the adhesive forces between the liquid and the tube or porous material.
- Adhesive forces are responsible for the rise of the liquid in the capillary tube.
- As the temperature increases, the adhesive forces weaken, leading to a decrease in the capillary rise.

3. Experimental Observations:
- Experimental studies have shown that the capillary rise of various liquid fluids decreases with an increase in temperature.
- This decrease in capillarity is more pronounced for liquids with low surface tension and weak adhesive forces.

Conclusion:
In conclusion, the capillarity of liquid fluids decreases with a rise in temperature. This is due to the decrease in surface tension and adhesive forces between the liquid and the capillary tube or porous material. This decrease in capillarity has practical implications in various fields, including civil engineering, where capillary rise in building materials can lead to moisture problems.