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Engineering ToolBox > Surface Tension

Surface tension of some common liquids like water, mercury, oils and more

Surface tension is the energy required to stretch a unit change of a surface area. Surface tension will form a drop of liquid to a sphere since the sphere offers the smallest area for a definite volume.

Surface tension can be defined as

σ = F_s / l  (1)

where

σ = surface tension (N/m)

F_s =  stretching force (N)

l = unit length (m)

Alternative Units

Alternatively, surface tension is typically measured in dynes/cm, which is

• the force in dynes required to break a film of length 1 cm

or as surface energy J/m² or alternatively ergs per square centimeter.

• 1 dynes/cm = 0.001 N/m = 0.0000685 lb_f/ft = 0.571 10^-5 lb_f/in = 0.0022 poundal/ft = 0.00018 poundal/in = 1.0 mN/m = 0.001 J/m² = 1.0 erg/cm² = 0.00010197 kg_f/m

Common Imperial units used are lb/ft and lb/in.

Surface Tension of Water

Water surface tension at different temperatures can be taken from the table below:

Surface Tension of some common Fluids

• benzene : 0.0289 (N/m)
• diethyl ether : 0.0728 (N/m)
• carbon tetrachloride : 0.027 (N/m)
• chloroform : 0.0271 (N/m)
• ethanol : 0.0221 (N/m)
• ethylene glycol : 0.0477 (N/m)
• glycerol : 0.064 (N/m)
• mercury : 0.425 (N/m)
• methanol : 0.0227 (N/m)
• propanol : 0.0237 (N/m)
• toluene : 0.0284 (N/m)
• water at 20^oC : 0.0729 (N/m)