Surface Tension
Capillary Height
Young’s Equation - droplet of water on a flat surface (can we make this work for a seed in water)
Compton’s Scattering Formula - “1923 A Quantum Theory of the Scattering of X-Rays by Light Elements” get’s us the very small unit of length of an Angstrom and a formula with Cos Theta. Compton scattering led to “proof” that light acts as waves and particles
Look at Young’s Equation with respect to Compton’s Wavelength Formula
Piere Simon Laplace - Young Laplace Equation
Gibbs Free Energy equation
Surface Tension
Surface tension is a fundamental property of liquids, stemming from the cohesive forces between molecules at the interface between the liquid and another medium, such as air or a solid surface. It is defined as the force per unit length acting perpendicular to an imaginary line drawn on the liquid surface. The cohesive forces between the liquid molecules create a net inward force at the surface, resulting in the minimization of surface area and the formation of a distinct surface layer. This cohesive network of molecules gives rise to the unique behavior associated with surface tension. It manifests in various phenomena, including capillary action, where liquids rise or fall in narrow tubes against gravity, the formation of droplets or beading on surfaces, and the ability of certain objects to float on the liquid surface. Surface tension is a subject of extensive scientific research and finds applications in a wide range of fields, from fluid dynamics and materials science to biology and engineering.
γ = F / L
where:
γ is the surface tension,
F is the force exerted parallel to the surface of the liquid, and
L is the length over which that force is distributed.
The SI unit for surface tension is newtons per meter (N/m), but it can also be expressed in smaller units such as millinewtons per meter (mN/m) or dynes per centimeter (dyn/cm).
Deep Dive on Surface Tension
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Surface tension is the property of a liquid that arises due to cohesive forces between molecules at the surface of the liquid.
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Surface tension caused by the imbalance of intermolecular forces experienced by the molecules at the liquid surface.
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“Surface tension is at the origin of the overpressure existing in the interior of drops and bubbles.
The smaller the drop, therefore, the greater its inner pressure.”
Agnes Pockels (1862–1935) was a German physicist known for her significant contributions to the field of surface science. Despite her lack of formal higher education in physics or access to a scientific laboratory, Pockels made substantial breakthroughs in understanding the properties of surface tension.
Pockels' work was primarily focused on surface tension in liquids. After observing her household chores, such as washing dishes, she became interested in the properties of soap bubbles and films. This led to her invention of a device she called a "surface trough". This simple yet effective tool enabled her to measure the surface tension of water and other liquids with a remarkable degree of precision.
She conducted experiments at home and corresponded about her findings with leading scientists of the time. Despite facing many barriers due to her gender and lack of formal education, her work eventually gained recognition. She corresponded with Irish physicist Lord Rayleigh, who was highly impressed with her work and helped publish her findings in the scientific journal "Nature" in 1891. This publication marked the first of many for Pockels, and her contributions have since become foundational to the field of surface science.
Agnes Pockels' story is a great example of the potential for scientific discovery outside of traditional academic contexts and a testament to the tenacity and passion of self-taught researchers. Her work laid a foundation for future research in the fields of chemistry and physics, particularly in understanding the properties of liquid surfaces.
"Surface Tension" (1891) in "Nature" - This is the first scientific paper she published, with the assistance of Lord Rayleigh. It introduced her experimental technique and initial findings regarding surface tension.
"Surface Tension in Mixtures" (1892) in "Nature" - In this paper, Pockels discussed the impact of adding various substances to water and the resulting changes in surface tension.
Surface Work
Surface work is an important concept in the field of physical chemistry, particularly in the study of fluid interfaces. It is defined as the work done to increase the surface area of a liquid or a phase interface, and it is directly related to the property known as surface tension. Surface work provides insights into various natural and industrial processes, ranging from the formation of droplets and bubbles to the stability of foams and emulsions. Understanding surface work can help in the optimization of such processes, which have applications in diverse areas like materials science, oil recovery, food science, and pharmaceuticals. The mathematical description of surface work plays a crucial role in the formulation of models to predict the behavior of interfaces under different physical and chemical conditions.
REFERENCES
BOOKS COMING FROM MOBIUS
Rowlinson, J. S., Widom, B., Rowlinson, J. S. (2013). Molecular Theory of Capillarity. United States: Dover Publications.
Another book on Surface Tension
At least two books on Agnes Pockels
Molten SaltsMolten Salts, Website or Online DataVolume 2, Section 1. Electrochemistry of Molten Salts: Gibbs Free Energies and Excess Free Energies From Equilibrium-type Cells ; Section 2. Surface Tension Data
https://permanent.fdlp.gov/lps120174/NSRDS-NBS281.pdf
Tiny Droplets with Ice Structure at Room Temperature
This research, conducted by scientists from EPFL (École polytechnique fédérale de Lausanne) in collaboration with the AMOLF institute in the Netherlands, provides new insights into the behavior of nanometric-sized water droplets. These tiny droplets, with a size of 100 nm, are found in various environments such as the air, within our bodies, and in the earth.
Ordered Surface Molecules: The researchers discovered that the water molecules on the surface of these tiny droplets are much more ordered than expected. This level of order is not typical of water at room temperature, but rather resembles supercooled water or ice, where water molecules have very strong hydrogen bond interactions.
Unique Examination Method: The team developed a unique method to examine the surface of these droplets. They overlapped ultrashort laser pulses in a mixture of water droplets in liquid oil and detected photons that were scattered only from the interface. This allowed them to determine the structure of the interface.
Implications for Various Fields: The findings could have significant implications for understanding various atmospheric, biological, and geological processes. The chemical properties of these nanometric water droplets depend on the organization of water molecules on their surface. Therefore, understanding this organization is crucial.
Future Research: The team plans to further investigate the surface properties of water droplets by adding salt, which would provide a more realistic model of marine aerosols. The addition of salt could either enhance or reduce the strength of the water network, or it might not have any effect at all.
In summary, this research provides valuable insights into the behavior of nanometric water droplets, particularly the surprising order of water molecules on their surface, which could have wide-ranging implications for various scientific field.
https://actu.epfl.ch/news/water-is-surprisingly-ordered-on-the-nanoscale/
Addition of a Solid
Capillarity & Wetting
Capillarity
Capillarity, also known as capillary action, is a phenomenon in fluid dynamics where liquids spontaneously rise or fall in a narrow tube, or capillary, due to intermolecular forces. It's a balance of adhesive forces (the interaction between the liquid and the surface of the tube) and cohesive forces (the interaction between molecules of the liquid itself).
This principle is visible in numerous instances in nature and technology. It plays a crucial role in the absorption of water in plants, where water rises from the roots to the rest of the plant through capillary action in tiny vessels. It's also seen in how a sponge absorbs water or how a paintbrush wicks up paint.
The height to which the liquid rises or falls in a capillary tube depends on factors like the liquid's surface tension, the diameter of the tube, the angle of contact between the liquid and the tube's surface, and the acceleration due to gravity. This capillary rise or fall can be calculated using the Jurin’s law in case of a simple cylindrical tube.
James Jurin's law, often called Jurin's law, is a simple mathematical model that describes the height a liquid will rise or fall in a narrow capillary tube due to capillary action. It's named after James Jurin, a British physician and scientist who formulated it in the early 18th century. The law is as follows:
h = (2 * γ * cos(θ)) / (ρ * g * r)
where:
h is the height liquid rises or falls
γ is the liquid-air surface tension
θ is the contact angle between the liquid and the surface of the tube
ρ is the density of the liquid
g is the acceleration due to gravity
r is the radius of the tube
This law assumes that the tube is narrow and the height of the liquid column is small compared to the radius of the tube.
Wettability
Wettability refers to the ability of a liquid to maintain contact with a solid surface, resulting from the interplay between adhesive and cohesive forces. In simpler terms, it's a measure of how well a liquid can "wet" or spread across a surface.
Wettability is commonly evaluated by the contact angle, which is the angle where a liquid/vapor interface meets a solid surface. The lower the contact angle, the higher the wettability of the surface by the liquid.
For instance, if the contact angle is less than 90 degrees, the liquid tends to spread over the surface, indicating that the surface is hydrophilic (water-attracting). On the other hand, if the contact angle is greater than 90 degrees, the liquid tends to bead up and roll off, indicating that the surface is hydrophobic (water-repelling).
Young's equation describes the contact angle a liquid forms with a solid surface. This contact angle is a measure of the wettability of the solid by the liquid. Young's equation is:
γ_sv = γ_sl + γ_lv * cos(θ)
where:
γ_sv is the interfacial tension between the solid and vapor
γ_sl is the interfacial tension between the solid and liquid
γ_lv is the interfacial tension (or surface tension) between the liquid and vapor
θ is the contact angle
This equation is named after Thomas Young, a British scientist who formulated it in the early 19th century. It's particularly useful for understanding phenomena like how water beads up or spreads out on different surfaces. The contact angle θ used in Jurin's law is the same one described by Young's equation.
Examples in Geology
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EXPLORE MORE - in general cristoballite is high temperature, structure is very condensed compared to quartz.
Can this be used as an analogy to ice and water with water being a condensed cubic structure and ice is hexagonal, water can only sustain that shape at high temperature/kinetic energy.
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