Solution Chemistry

Author(s):  
Christopher O. Oriakhi

A solution is a homogeneous mixture of two or more substances. It is usually made up of a solute and a solvent. Generally, Solute+Solvent = Solution A solute is any substance that is dissolved in a solvent. For example, when granulated sugar dissolves in water to give a clear sugar solution, the sugar is the solute, while water is the solvent. Relative to the solvent, a solute is usually present in small amounts. A solvent is any substance in which a solute dissolves. It is usually the part of the solution that is present in the largest amount. Two liquids are said to be miscible if they form a single phase (homogeneous solution) or dissolve in each other in all proportions. For example, ethanol and water are miscible. If two liquids do not form a single phase (or do not dissolve in each other) in any appreciable amount, they are said to be immiscible. For example, water and oil are immiscible. When mixed, they separate into two distinct layers. Substances that are only slightly soluble in a given solvent are said to be insoluble. An aqueous solution is one in which water is the solvent. A dilute solution is one that contains a small amount of solute compared to the maximum amount the solvent can dissolve at that temperature. A concentrated solution is one that contains a large amount of solute compared to the maximum amount the solvent can dissolve at that temperature. A saturated solution is one that is in equilibrium with undissolved solute at a given temperature and pressure: Solute(solid) ⇌ Solute(dissolved) In other words, it contains the maximum amount of solute that can be dissolved at that particular temperature. An unsaturated solution contains less solute than the maximum amount (saturated solution) possible at the same temperature. A supersaturated solution is a solution that contains more solute than the saturated solution at the same temperature. This type of solution is very unstable. When it is agitated, or a speck of the solute is added to it, the excess solute will begin to crystallize out rapidly from the solution until the concentration becomes equal to that of the saturated solution.

Author(s):  
V.P. Bondarenko ◽  
O.O. Matviichuk

Detail investigation of equilibrium chemical reactions in WO3–H2O system using computer program FacktSage with the aim to establish influence of temperature and quantity of water on formation of compounds of H2WO4 and WO2(OH)2 as well as concomitant them compounds, evaporation products, decomposition and dissociation, that are contained in the program data base were carried out. Calculations in the temperature range from 100 to 3000 °С were carried out. The amount moles of water added to 1 mole of WO3 was varied from 0 to 27. It is found that the obtained data by the melting and evaporation temperatures of single-phase WO3 are in good agreement with the reference data and provide additionally detailed information on the composition of the gas phase. It was shown that under heating of 1 mole single-phase WO3 up to 3000 °С the predominant oxide that exist in gaseous phase is (WO3)2. Reactions of it formation from other oxides ((WO3)3 and (WO3)4) were proposed. It was established that compound H2WO4 is stable and it is decomposed on WO3 and H2O under 121 °C. Tungsten Oxide Hydrate WO2(OH)2 first appears under 400 °С and exists up to 3000 °С. Increasing quantity of Н2О in system leads to decreasing transition temperature of WO3 into both liquid and gaseous phases. It was established that adding to 1 mole WO3 26 mole H2O maximum amount (0,9044–0,9171 mole) WO2(OH)2 under temperatures 1400–1600 °С can be obtained, wherein the melting stage of WO3 is omitted. Obtained data also allowed to state that that from 121 till 400 °С WO3–Н2O the section in the О–W–H ternary system is partially quasi-binary because under these temperatures in the system only WO3 and Н2O are present. Under higher temperatures WO3–Н2O section becomes not quasi-binary since in the reaction products WO3 with Н2O except WO3 and Н2O, there are significant amounts of WO2(OH)2, (WO3)2, (WO3)3, (WO3)4 and a small amount of atoms and other compounds. Bibl. 12, Fig. 6, Tab. 5.


1988 ◽  
Vol 43 (5) ◽  
pp. 529-532 ◽  
Author(s):  
Raimund Schmid ◽  
Johannes Beck ◽  
Joachim Strähle

Cs+(tolN5tol)- (1) is formed as a yellow crystalline precipitate after addition of a concentrated aqueous solution of CsCl to a concentrated solution of 1,5-Bis(p-tolyl)pentaazadiene(1,4) in ammonia. 1 crystallizes in the orthorhombic space group Pccn with a = 3169(1), b = 434.3(2), c = 1109.4(7) pm, Z = 4. The structure contains (tolN5tol)- anions and Cs+ cations both occupying two-fold axes. The all-trans N5 zigzag chain is planar with localized double bonds N1 - N2 and N2′ - N1′ of 127.7 pm and shortened single bonds N2-N3 and N3-N2′ of 136.9 pm. The tolyl substituents are titled by 25.5° against the plane of the N atoms. Cs+ is surrounded in a square antiprismatic arrangement by eight N atoms of four N5 chains with distances Cs-N in the range of 314.6 to 366.2 pm.


Polyhedron ◽  
1991 ◽  
Vol 10 (3) ◽  
pp. 377-387 ◽  
Author(s):  
John R. Duffield ◽  
David R. Williams ◽  
Ivan Kron

2000 ◽  
pp. 109-172 ◽  
Author(s):  
Lucia Alderighi ◽  
Peter Gans ◽  
Stefano Midollini ◽  
Alberto Vacca

2020 ◽  
Vol 49 (9-10) ◽  
pp. 1279-1289
Author(s):  
Leif Häggman ◽  
Cecilia Lindblad ◽  
Anders Cassel ◽  
Ingmar Persson

Abstract Removal of metal compounds from wastewater using processes where metals can be removed and valuable chemicals recycled is of significant industrial importance. Chelating surfactants are an interesting group of chemicals to be used in such applications. Carboxylated polyamines are a promising group to be used in such processes. To apply carboxylated polyamines as chelating surfactants, detailed knowledge of the solution chemistry, including complex formation, kinetics and structures of pure fundamental systems, is required. In this study zinc(II) alkyl-N-iminodiacetate systems with varying length of the alkyl chain have been studied. Acidic and stability constants have been studied by potentiometry, and the structures of both solids and aqueous solutions have been determined by EXAFS. Zinc(II) forms two strong complexes with alkyl-N-iminodiacetates in aqueous solution. In an attempt to determine the acidic constants of these complexes, the deprotonation of the nitrogen atom in the complex bound ligands, it was observed that this reaction is very slow and no accurate values could be obtained. The bis(alkyl-N-iminodiacetato)zincate(II) complexes take, however, up two protons in the pH region 3–7, which means that this complex is approximately singly protonated in the pH region 3–7 and doubly protonated at pH < 3. The bis(n-hexyl-N-iminodiacetato)zincate(II) complex at pH = 13 has a distorted octahedral configuration with four short strong Zn–O bonds at 2.08(1) Å, while the Zn–N bonds are weaker at much longer distance, 2.28(2) Å. Similar configurations are also found in most reported structures of zinc(II) complexes with carboxylated amines/polyamines. The singly protonated complex seems to be five-coordinate, with four Zn–O bond distances at ca. 2.03 Å, and a single Zn–N bond distance in the range 2.15–2.25 Å. The relationship between the structure of the protonated bis(n-hexyl-N-iminodiacetato)zincate(II) complex and the slow kinetics in the region pH = 3–7 are discussed.


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