水对分子的离子热合成的影响
Huaijun Ma1, Zhijian Tian, Renshun Xu
1Dalian Institute of Chemical Physics, Dalian 116023, China.
Journal of the American Chemical Society
|June 6, 2008
概括
合成酸分子像AlPO4-11和AlPO4-5没有水是可能的. 添加少量水可以显著加快这些重要材料的结晶过程.
科学领域:
- 材料科学 材料科学 材料科学
- 无机化学 无机化学
- 催化剂是一种催化剂.
背景情况:
- 酸 (AlPO4) 分子在催化和分离过程中至关重要.
- 传统合成通常涉及水,但对于特定应用,正在探索无水路线.
- 了解合成参数是控制AlPO4属性的关键.
研究的目的:
- 为了研究AlPO4-11和AlPO4-5分子的离子热合成.
- 探索水在合成过程中的作用.
- 为了确定增强结晶运动的条件.
主要方法:
- 使用无水 NH4H2PO4,伪波胺 (AlOOH) 和 NH4F 的离子热合成.
- 在合成过程中水含量的系统变化.
- 合成材料的特征 (隐含).
主要成果:
- AlPO4-11和AlPO4-5分子 successfully成功地在没有水的情况下以离子热方式合成.
- 合成过程表现出自身催化特性.
- 添加水 (摩尔比H2O/Al=1) 显著增强了结晶动力学.
结论:
- 无水离子热合成AlPO4-11和AlPO4-5是可行的.
- 水在加速这些分子的结晶中起着至关重要的作用.
- 控制式添加水提供了一种优化合成效率的方法.
相关概念视频
Common Ion Effect
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 Châtelier’s principle. Consider the dissolution of silver iodide:
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...
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...
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:


