vacancy |
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Vacancy is a missing atom or ion in a crystal lattice. |
van der Waals' equation |
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Van der Waals' equation is an equation of state for fluids which takes the form:
where p is pressure, Vm is molar volume, T is temperature, R is the molar gas constant, and a and b are characteristic parameters of the substance which describe the effect of attractive and repulsive intermolecular forces. |
van der Waals' force |
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Van derWaals' force is the weak attractive force between two molecules which arises from electric dipole interactions. It can lead to the formation of stable but weakly bound dimer molecules or clusters. They are named after the Dutch physicist Johannes van der Waals (1837-1923). |
van't Hoff equation |
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Van't Hoff equation is the equation expressing the temperature dependence of the equilibrium constant K of a chemical reaction:
where ΔrH° is the standard enthalpy of reaction, R the molar gas constant, and T the temperature. |
vapor pressure |
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Vapor pressure is the pressure of a gas in equilibrium with a liquid (or, in some usage, a solid) at a specified temperature. |
volt |
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Volt (V) is the SI derived unit of electric potential. One volt is the difference of potential between two points of an electical conductor when a current of 1 ampere flowing between those points dissipates a power of 1 watt. It is named after the Italian physicist Alessandro Volta (1745-1827). |
volume fraction |
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Volume fraction (φj) is defined as
where Vj is the volume of the specified component and the Vi are the volumes of all the components of a mixture prior to mixing. |
watt |
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Watt (W) is the SI derived unit of power. One watt is a power of one joule per second (W = J/s). It is named after the Scottish engineer James Watt (1736-1819). |
weak acid |
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Weak acid is an acid that incompletely dissociated in aqueous solution. |
weber |
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Weber (Wb) is the SI derived unit of magnetic flux. The weber is the magnetic flux which, linking a circuit of one turn, produces in it an electromotive force of one volt as it is reduced to zero at a uniform rate in one second (Wb = V∙s). The unit is named after the German scientist W.E. Weber (1804-1891). |
weight |
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Weight is a measure of the pull of gravitational force on an object. It is directly proportional to mass. |
Wöhler's synthesis |
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Wöhler's synthesis is a synthesis of urea performed by German chemist Friedrich Wöhler (1800-1882) in 1828. He discovered that urea (CO(NH2)2) was formed when a solution of ammonium isocyanate (NH4NCO) was evaporated. At the time it was believed that organic substances such as urea could be made only by living organisms, and its production form an inorganic compound was a notable discovery. |
