溶解度平衡
“溶解度产品”一词是指廉价的可溶性盐。它是化合物解离产生的离子摩尔浓度(提高到适当的功率)的最大乘积。溶解度积在任何给定温度下都是恒定的。溶度积值越低,溶解度越低,溶度积值越高,溶解度越高。
溶解度积常数
溶度积常数是固体物质溶解到水溶液中的平衡常数。它由符号 K sp表示。溶度积是一种平衡常数,其值随温度而变化。由于溶解度增加,K sp通常随着温度升高而升高。
Solubility is defined as the ability of a substance known as a solute to dissolve in a solvent and create a solution. The solubility of ionic substances in water (which dissociate to form cations and anions) varies greatly.
有些物质是高度可溶的,甚至可能从环境中吸收水分,而另一些则完全不溶。
溶解度积的意义
- 盐的晶格焓和溶液中离子的溶剂化焓是决定溶解度的最关键因素。
- 当盐溶解在溶剂中时,溶质的强大吸引力必须通过离子和溶剂之间的相互作用(离子的晶格焓)来抵消。
- 离子溶剂化焓始终为负,表明在此过程中释放了能量。
- 溶剂化焓或溶剂化过程中释放的能量由溶剂的组成决定。
- 由于非极性溶剂的溶剂化焓低,这种能量不足以克服晶格焓。
- 结果,盐不能溶解在非极性溶剂中。因此,为了使盐溶解在溶剂中,其溶剂化焓必须大于其晶格焓。
- 温度对溶解度的影响:我们可以通过提高温度来增加溶质的溶解度。水一般在20℃或100℃溶解溶质。通过提高温度,可溶性固体或液体物质可以完全液化。然而,在气态物质的情况下,温度对溶解度有相反的影响,这意味着随着温度的升高,气体会膨胀并从溶剂中逸出。
液体在液体中的溶解度
- 除了少数例外,水被称为通用溶剂,因为它几乎可以溶解所有溶质。物质的溶解度会受到多种因素的影响。溶解度是溶质分子和溶剂分子之间新键的产生。
- 就数量而言,溶解度是在给定温度下溶解在已知浓度溶剂中的最大溶质浓度。根据它们在溶剂中溶解的浓度,溶质分为高溶、微溶或不溶。
- 如果溶质能以 0.1g 或更高的浓度溶解在 100ml 溶剂中,则称其为可溶的。虽然已知溶剂中小于 0.1 g 的浓度是微溶的。因此,众所周知,溶解度是一种以克/升 (g/L) 为单位的定量表述。
- 溶解度可用于创建各种解决方案。饱和溶液是一种特定量的溶质在给定温度下完全溶于溶剂的溶液。另一方面,过饱和溶液是在相同温度下溶解一定量的溶质并且溶质开始盐析或沉淀的溶液。
示例问题
问题1:溶解度和溶度积常数有什么区别?
回答:
A substance’s solubility in a solvent is the total amount of solute that can be dissolved in the solvent at equilibrium. The solubility product constant, on the other hand, is an equilibrium constant that offers information on the equilibrium between the solid solute and its constituent ions that are dissociated across the solution.
问题2:氯化钙的溶度积常数是多少?
回答:
CaCl2 is the chemical formula for calcium chloride. One calcium chloride molecule dissociates into one calcium cation and two chloride anions when dissolved in polar liquids. This equilibrium reaction is illustrated below.
CaCl2 ⇌ Ca2+ + 2Cl–
As a result, the solubility product constant can be written as:
Ksp = [Ca2+][Cl–]2
问题3:影响Ksp值的因素有哪些?
回答:
Some key parameters influencing the solubility product constant are:
- The effect of common ions (the presence of a common ion lowers the value of Ksp).
- The ion-diversity effect (if the ions of the solutes are uncommon, the value of Ksp will be high).
- Ion-pairs are present.
问题 4:溶解度与浓度有何关系 为什么了解物质的溶解度很重要?
回答:
The amount of solute that can dissolve in a given amount of solvent at a given temperature is referred to as solubility. A solution’s concentration is the amount of solute in a given amount of solution. A dilute solution has a low solute concentration. Solubility determines how chemicals dissolve into one another. The solute is the material that dissolves into the other, and the solvent is the substance that is dissolved into. These factors can either speed up or slow down the rate of solubility of certain compounds.
问题5:气体是否也溶于水,我们也可以称它们为溶质吗?
回答:
Water is an excellent solvent that is abundant on Earth. It is soluble in a wide range of substances. Everyone is familiar with solid-state compounds that can dissolve in water. Surprisingly, several chemicals that naturally exist in a gaseous state are also dissolved in water. Canon dioxide is a well-known gas for this purpose, and it is widely utilised in the manufacturing of soda water or soft drinks. Oxygen is also soluble in water in small levels but is critical to the living system that all bodies of water support. Another known gas that dissolves in water is ammonia.