Calculation Of Surface Tension By Capillary Rise Method

Surface Tension Formula:

\[ \gamma = \frac{\rho \cdot g \cdot r \cdot h}{2} \]

Density (ρ):

kg/m³

Gravity (g):

m/s²

Radius (r):

Height (h):

Surface Tension (γ):

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1. What is Surface Tension?

Surface tension is the elastic tendency of a fluid surface which makes it acquire the least surface area possible. It is caused by the cohesive forces between liquid molecules at the surface.

2. How Does the Capillary Rise Method Work?

The capillary rise method uses the formula:

\[ \gamma = \frac{\rho \cdot g \cdot r \cdot h}{2} \]

Where:

\( \gamma \) — Surface tension (N/m)
\( \rho \) — Density of the liquid (kg/m³)
\( g \) — Acceleration due to gravity (9.8 m/s²)
\( r \) — Radius of the capillary tube (m)
\( h \) — Height of liquid rise in the capillary (m)

Explanation: This method measures the height to which a liquid rises in a narrow capillary tube due to surface tension forces.

3. Importance of Surface Tension Calculation

Details: Surface tension measurements are crucial in various fields including physics, chemistry, biology, and engineering. It helps understand fluid behavior, capillary action, and is important in processes like wetting, emulsification, and foaming.

4. Using the Calculator

Tips: Enter density in kg/m³, gravity in m/s² (default is 9.8), radius in meters, and height in meters. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range of surface tension values?
A: Surface tension values typically range from 20-75 mN/m for common liquids at room temperature.

Q2: Why does water rise in a capillary tube?
A: Water rises due to adhesive forces between water molecules and the glass tube being stronger than cohesive forces between water molecules.

Q3: What factors affect surface tension measurements?
A: Temperature, impurities, and the nature of the liquid and solid surface can all affect surface tension measurements.

Q4: Can this method be used for all liquids?
A: This method works best for liquids that wet the capillary tube material. For non-wetting liquids, the capillary depression method should be used.

Q5: How accurate is the capillary rise method?
A: With precise measurements of radius and height, this method can provide accurate results, though it requires clean equipment and careful technique.