Work of Cohesion Formula:
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Definition: Work of Cohesion is defined as the surface free energy increased by separating a column of pure liquid into two halves.
Purpose: It quantifies the energy required to overcome intermolecular forces at a liquid's surface.
The calculator uses the formula:
Where:
Explanation: The formula relates surface tension to the energy required to separate liquid molecules, accounting for molecular density via Avogadro's number and molar volume.
Details: Understanding work of cohesion helps in studying liquid properties, surface phenomena, and designing processes like coating, wetting, and adhesion.
Tips: Enter the surface tension (default 0.073 N/m for water at 20°C) and molar volume (default 22.4×10⁻⁶ m³/mol for ideal gases at STP). All values must be > 0.
Q1: What are typical surface tension values?
A: Water at 20°C has 0.073 N/m, mercury 0.485 N/m, and ethanol 0.022 N/m.
Q2: Why is Avogadro's number used in this formula?
A: It relates macroscopic measurements to molecular-scale interactions.
Q3: How does temperature affect work of cohesion?
A: Generally decreases with temperature as intermolecular forces weaken.
Q4: Can this be used for mixtures?
A: No, this formula applies only to pure substances.
Q5: What's the relationship to surface energy?
A: Work of cohesion equals twice the surface energy for a liquid.