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In 1805, Thomas Young defined the contact angle θ by analyzing the forces acting on a fluid droplet resting on a solid surface surrounded by a gas. [8] A liquid droplet rests on a solid surface and is surrounded by gas. The contact angle, θ C, is the angle formed by a liquid at the three-phase boundary where the liquid, gas, and solid intersect.
Among the forces that govern drop formation: cohesion, surface tension, Van der Waals force, Plateau–Rayleigh instability. Water, for example, is strongly cohesive as each molecule may make four hydrogen bonds to other water molecules in a tetrahedral configuration. This results in a relatively strong Coulomb force between molecules. In ...
[1] [2] The word hydrophobic literally means "water-fearing", and it describes the segregation of water and nonpolar substances, which maximizes the entropy of water and minimizes the area of contact between water and nonpolar molecules. In terms of thermodynamics, the hydrophobic effect is the free energy change of water surrounding a solute. [3]
Ammonia solution, also known as ammonia water, ammonium hydroxide, ammoniacal liquor, ammonia liquor, aqua ammonia, aqueous ammonia, or (inaccurately) ammonia, is a solution of ammonia in water. It can be denoted by the symbols NH 3 (aq). Although the name ammonium hydroxide suggests a salt with the composition [NH + 4][OH −
An alternative quantitative measure is the heat of formation of the Lewis acid-base adduct in a non-coordinating solvent. The ECW model is quantitative model that describes and predicts the strength of Lewis acid base interactions, -ΔH . The model assigned E and C parameters to many Lewis acids and bases.
In even a slight presence of water, carbonic acid dehydrates to carbon dioxide and water, which then catalyzes further decomposition. [6] For this reason, carbon dioxide can be considered the carbonic acid anhydride. The hydration equilibrium constant at 25 °C is [H 2 CO 3]/[CO 2] ≈ 1.7×10 −3 in pure water [12] and ≈ 1.2×10 −3 in ...
The polarized form of the water molecule, H + OH −, is also called hydron hydroxide by IUPAC nomenclature. [106] Water substance is a rare term used for H 2 O when one does not wish to specify the phase of matter (liquid water, water vapor, some form of ice, or a component in a mixture) though the term water is also used with this general ...
Crystalline benzoic acid shown here is a solid and an acid, but, in the context of this article, it is not a "solid acid", which are polymeric materials and typically stronger acids. Examples of inorganic solid acids include silico-aluminates (zeolites, alumina, silico-aluminophosphate), and sulfated zirconia.