What is Surface energy: Definition and 23 Discussions

Surface free energy or interfacial free energy or surface energy quantifies the disruption of intermolecular bonds that occurs when a surface is created. In the physics of solids, surfaces must be intrinsically less energetically favorable than the bulk of a material (the molecules on the surface have more energy compared with the molecules in the bulk of the material), otherwise there would be a driving force for surfaces to be created, removing the bulk of the material (see sublimation). The surface energy may therefore be defined as the excess energy at the surface of a material compared to the bulk, or it is the work required to build an area of a particular surface. Another way to view the surface energy is to relate it to the work required to cut a bulk sample, creating two surfaces. There is "excess energy" as a result of the now-incomplete, unrealized bonding at the two surfaces.
Cutting a solid body into pieces disrupts its bonds and increases the surface area, and therefore increases surface energy. If the cutting is done reversibly, then conservation of energy means that the energy consumed by the cutting process will be equal to the energy inherent in the two new surfaces created. The unit surface energy of a material would therefore be half of its energy of cohesion, all other things being equal; in practice, this is true only for a surface freshly prepared in vacuum. Surfaces often change their form away from the simple "cleaved bond" model just implied above. They are found to be highly dynamic regions, which readily rearrange or react, so that energy is often reduced by such processes as passivation or adsorption.

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  1. G

    Chemistry How to compute specific surface energy for cubes of varying sizes?

    I got these values but I wanted to make sure I was doing it the correct way a) 0.548 J/g for system of 1 µm cubes b) 9.131 x 10^19 J/g for system of 1 nm cubes c) 273.890 J/g for system of 1 nm radius spheres
  2. Dario56

    I How Does Surface Tension Balance Small Objects on Water Surface?

    When small object such as needle is put on the surface of water it displaces small amount of water which creates a depression under the object. Such depression increases surface area of the water because of which surface tension tends to decrease it. Explanation why surface tension balances the...
  3. Dario56

    Owens - Wendt Model for Surface Energy of Solid - Liquid Interface

    Owens - Wendt model is used for calculating surface energy on liquid - solid interface and it is given by following equation: $$ \gamma_{sl} = \gamma_s + \gamma_l -2(\sqrt {\gamma_l^d \gamma_s^d} + \sqrt {\gamma_l^p \gamma_s^p}) $$ So, if we use liquid and solid of known surface energy as well...
  4. Jacob Daniel

    Calculate the "surface energy" of succesively smaller cubes

    Homework Statement NaCl has a density of 2.16 g/cm3 and a surface energy of 2x10-5 J/cm2. Calculate the surface energy of 1 g of NaCl. Initially the complete 1 g is in the form of a single cube (of mass 1 g) and progressively broken into smaller cubes with sides of 0.1 cm, 0.01 cm, 10 μm, 1 μm...
  5. M

    A Fluids -- Surface Energy

    I'm studying thin fluid films, and the text writes free surface energy of a film (puddle) over domain ##(0,X)## can be expressed as $$E=\int_0^X \left[\frac{h_x^2}{2}+\omega(h)+G\frac{h^2}{2} \right]\, dx$$ where ##X## is a length that the thin film (puddle) rests on, ##h## is the height of the...
  6. D

    A Wulff construction for surface energy dependent on depth

    Hello, Using surface energy dependence on surface orientation it is possible to predict equilibrium crystal shape by applying Wulff construction. But I faced the problem when the surface energy depends not only on the surface orientation but also on the surface depth or surface termination and...
  7. V

    I Why does low surface energy imply hydrophobicity?

    I don't understand why materials with low surface energy are hydrophobic and viceversa. All I can find are quick phenomenological explanations that don't quite deal with the physical (microscopic) process going on. Could anyone provide a good microscopic picture of why it is that way? What's...
  8. G

    I Why does high surface energy of the solid have more wetting?

    Hello. Recently, I have read the article about plasma surface treatment. The article says contact of the plasma to the surface of the sample increases surface energy by transferring plasma energy to the surface. Then it is suddenly saying that wettability of some industrial ink or paints on...
  9. Raazi

    Surface Friction and Energy Modeling

    Hi, I am a student interested in wetting and super-hydrophobic surfaces. I am very new to this field and am a software engineer, and as such do not have strong mechanical or chemical background. I am trying to model contact angle and surface energy for super-hydrophobic surfaces. However my...
  10. AdityaDev

    Understanding Surface Tension and the Role of Force in U-Shape Wire Frames

    If I have a U-shape wire frame and it contains a straight sliding wire and I dip this in soap, a film forms between the sliding wire and the boundary of U shape frame. Why is the force due to surface tension F = 2Tl where l is length of sliding wire? They say there are 2 layers in contact...
  11. A

    Surface energy simple cubic crystal

    I want to calculate the surface energy for the (001) plane in a simple cubic lattice. My idea is this: When I cleave a simple cubic crystal I create 2 surfaces each sharing an amount of broken bonds. I want to find the amount of broken bonds per area, because I can associate an energy with...
  12. T

    Surface Energy of Microspheres: Help Needed!

    LS, During discussion with colleagues on a paper we hit a problem which we could not solve. Could someone help us out. Is the If surface energy/stress of a microsphere with a diameter of 5μm larger or smaller compared to the one of a 30μm microsphere. According to the Hamaker constant I guess...
  13. U

    Dispersive Component of Surface Energy

    Hello, I'm doing an MSc project concerned with the treatment of plastic polymers with an μ-APPJ. I have been getting a tonne of results on different plastics using an APPJ of He carrier gas with an Oxygen admixture of 1/2, 1 & 2%. However, in my analysis I'm unsure of what the dispersive...
  14. R

    Surface energy and adhesion

    Consider comparasion between same states and same type of materials. also consider the substrates to have same surface quality. a substance with higher cohesive force would have a higher surface energy. this should be because of the stronger cohesive forces between molecules as the molecule...
  15. T

    Fowkes model of surface energy

    Hello I need an answer for my Bachelor’s dissertation. In Fowkes model of surface energy, work of adhesion is defined as the sum of geometric mean of dispersive and nondispersive forces. In all articles, people say that the geometric mean comes from Berthelot combining rules, developed in...
  16. V

    Surface Energy Calculation: 8-24(πr^2S)

    hiii :) Homework Statement (Q)Air is pushed into a soap bubble of radius r to double its radius.If the surface tension of the soap solution is S, the work done in the process is <a>8(pie)(r)2(S) <b>12(pie)(r)2(S) <c>16(pie)(r)2(S) <d>24(pie)(r)2(S) Homework Equations Surface energy...
  17. Z

    Surface Energy of a Balloon

    Homework Statement What will happen to the surface energy of a balloon when the air inside it is heated at a constant pressure? The Attempt at a Solution I don't understand how will a balloon have surface energy. What is its origin? Is it due to the elastic forces of the stretched...
  18. H

    Fluid Mechanics : Ice cube melting and Surface Energy Que.

    Q. 1. if a ice cube is placed in a container containing liq on which it is floating. then is it possible that after ice melts, water level rises in vessel in any particular case. 2.Does heat evolves when water rises in a capillary. and how much heat is evolved in height of liq in capillary...
  19. H

    Fluid Mechanics : Ice cube melting and Surface Energy Que.

    I have a que. if a ice cube is placed in a container containing liq on which it is floating. then is it possible that after ice melts, water level rises in vessel in any particular case. Does heat evolves when water rises in a capillary. and how much heat is evolved in height of liq in...
  20. J

    Surface energy theoretical questions work shown

    1.) When woven material is dry, air will pass directly through. When immersed in water however, clothing can be used to trap air and provide buoyancy. a.) With the aid of the diagram, explain why this is so? need help explaining theoreticallly? b.) Give an eq. which can be used...
  21. I

    Surface Energy of Miller Index Cross Sections

    ℽ = ½Nbερa ℽ = surface energy Nb = number of broken bonds ε = bond strength ρa = surface atomic density ℽ{100} = (½)( 2 / a2 )(4)(ε) ℽ{110} = ( 5 / sqrt(2) )( ε / a2 ) ℽ{111} = (2sqrt(3))( ε / a2 ) the supplemental picture shows a cube with atoms at each corner and one atom in...
  22. T

    Understanding Surface Energy: A Beginner's Guide

    I checked Wiki and ran a forum search, yet I am in need of an explanation of "Surface Energy" that works for me. I'm clueless on the concept... (btw, just joined physics forums today, seems like a really cool community here...)
  23. S

    Earth science, surface energy balance

    Given the equation Q* = QH + QE + QG and the corresponding data (all fluxes in [W/m²]). How can I find the equivalent loss of stored soil liquid water expressed in [mm] (Note: the conversion factor is the density of liquid water, i.e. 1000 kg/m^3) Thanks very much for your help!:confused: