分子のイオン熱合成に対する水の影響
Huaijun Ma1, Zhijian Tian, Renshun Xu
1Dalian Institute of Chemical Physics, Dalian 116023, China.
Journal of the American Chemical Society
|June 6, 2008
まとめ
AlPO4-11やAlPO4-5のようなアルミニウムリン酸塩分子を水なしで合成することは可能である. 少量の水を加えると,これらの重要な材料の結晶化プロセスが大幅に加速します.
科学分野:
- 材料科学 材料科学とは
- 無機化学 無機化学とは
- カタリシス カタリシス カタリシス
背景:
- アルミニウムリン酸 (AlPO4) の分子は,触媒と分離において極めて重要です.
- 伝統的な合成には,しばしば水が含まれますが,特定の用途のために無水経路が探索されています.
- 合成パラメータを理解することは,AlPO4の性質を制御するための鍵です.
研究 の 目的:
- AlPO4-11およびAlPO4-5分子のイオン熱合成を調査する.
- 合成プロセスにおける水の役割を調査する.
- 結晶化運動の強化のための条件を決定する.
主な方法:
- 無水性NH4H2PO4,シドボヘミット (AlOOH),NH4Fを用いたイオン熱合成.
- 合成中の水分量の体系的な変化.
- 合成された材料の特徴 (暗示).
主要な成果:
- AlPO4-11とAlPO4-5の分子シーブは,水なしでイオン熱で成功して合成されました.
- 合成プロセスはオートカタリティックな特徴を示しています.
- 水 (モラ比H2O/Al=1) を加えることで結晶化運動が著しく改善された.
結論:
- AlPO4-11とAlPO4-5の無水イオン熱合成は可能である.
- 水は,これらの分子シートの結晶化を加速する上で重要な役割を果たします.
- 制御された水添加は,合成効率を最適化する方法を提供します.
関連する概念動画
Common Ion Effect
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Solubility Equilibria: Ionic Product of Water
Pure water is a weak electrolyte; only a small amount ionizes into hydrogen and hydroxide ions. At any given temperature, the concentration of undissociated water is almost constant, so the ionic product of water is the product of the hydrogen and hydroxide ion concentrations, denoted as Kw. The square root of Kw gives the individual ion concentrations.
The ionic product of water varies with temperature, and its value is 1.0 x 10−14 at standard experimental conditions. Per Le Chatelier's...
The ionic product of water varies with temperature, and its value is 1.0 x 10−14 at standard experimental conditions. Per Le Chatelier's...
Aqueous Solutions and Heats of Hydration
Water and other polar molecules are attracted to ions. The electrostatic attraction between an ion and a molecule with a dipole is called an ion-dipole attraction. These attractions play an important role in the dissolution of ionic compounds in water.
When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them. This process...
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Factors Affecting Solubility
Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a common ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the common ion effect, which is a consequence of the law of mass action that may be explained using Le Chȃtelier’s principle. Consider the dissolution of silver iodide:
Ionic Strength: Effects on Chemical Equilibria
The addition of an inert ionic compound increases the solubility of a sparingly soluble salt. For example, adding potassium nitrate to a saturated solution of calcium sulfate significantly enhances the solubility of calcium sulfate. Le Châtelier's principle cannot predict this shift in the equilibrium. Instead, this could be explained in terms of changes in the effective concentration of the ions in solution in the presence of added inert salt.
In this solution, the primary cation—the calcium...
In this solution, the primary cation—the calcium...
Precipitation of Ions
Predicting Precipitation
The equation that describes the equilibrium between solid calcium carbonate and its solvated ions is:
The equation that describes the equilibrium between solid calcium carbonate and its solvated ions is:


