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The Margules activity model is a simple thermodynamic model for the excess Gibbs free energy of a liquid mixture introduced in 1895 by Max Margules. [1] [2] After Lewis had introduced the concept of the activity coefficient, the model could be used to derive an expression for the activity coefficients of a compound i in a liquid, a measure for the deviation from ideal solubility, also known as ...
Platinum is a chemical element; it has symbol Pt and atomic number 78. It is a dense , malleable , ductile , highly unreactive, precious , silverish-white transition metal . Its name originates from Spanish platina , a diminutive of plata "silver".
A simple nitrite test can be performed by adding 4 M sulfuric acid to the sample until acidic, and then adding 0.1 M iron(II) sulfate to the solution. A positive test for nitrite is indicated by a dark brown solution, arising from the iron-nitric oxide complex ion.
The symmetry of a carbon dioxide molecule is linear and centrosymmetric at its equilibrium geometry. The length of the carbon–oxygen bond in carbon dioxide is 116.3 pm, noticeably shorter than the roughly 140 pm length of a typical single C–O bond, and shorter than most other C–O multiply bonded functional groups such as carbonyls. [19]
Mole Day originated from a celebration by educator Margaret Christoph. [5] She wrote an article about her experiences in The Science Teacher in the 1980s. [6] Inspired by this article, Maurice Oehler, a high school chemistry teacher from Prairie du Chien, Wisconsin, founded the National Mole Day Foundation (NMDF) on May 15, 1991.
In comparison, the LD 50 of sodium chloride (table salt) is 3.75 g/kg. Intravenously, the LD 50 of potassium chloride is far smaller, at about 57.2 mg/kg to 66.7 mg/kg; this is found by dividing the lethal concentration of positive potassium ions (about 30 to 35 mg/kg) [ 37 ] by the proportion by mass of potassium ions in potassium chloride ...
a = 266.46 pm c = 494.55 pm (at 20 °C) [3] ... Zinc is a chemical element with the symbol Zn and atomic ... Zinc chemistry resembles that of the late first-row ...
Humans exposed to as little as 0.01 mg/m 3 or less in air exude a foul garlic-like odor known as "tellurium breath". [24] [94] This is caused by the body converting tellurium from any oxidation state to dimethyl telluride, (CH 3) 2 Te, a volatile compound with a pungent garlic-like smell. Volunteers given 15 mg of tellurium still had this ...