19.11 溶性产品常量(Ksp)

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  溶解性产品常量(Ksp)

  

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  No more weighing!
  ::别再称重了!

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  At one time, a major analytical technique was gravimetric analysis. An would be precipitated out of solution, purified, and weighed to determine the amount of that ion in the original material. As an example, measurement of Ca ²⁺ involved dissolving the sample in water, precipitating the calcium as calcium oxalate, purifying the precipitate , drying it, and weighing the final product. Although this approach can be very accurate (atomic weights for many were determined this way), the process is slow, tedious, and prone to a number of errors in technique. Newer methods are now available that measure minute amounts of calcium ions in solution without the long, involved gravimetric approach.
  ::有一次,一项主要的分析技术是重力分析。 一种主要的分析技术是重力分析。 一种分析技术会由溶液、净化和权衡而产生,以确定原始材料中的离子数量。 举例来说,Ca2+的测量涉及将样本溶解到水中,催化钙作为氯化钙,净化沉淀物,烘干它,并权衡最终产品。 虽然这种方法可以非常精确(许多人的原子重量是按这个方法确定的 ) , 这一过程缓慢、 乏味, 容易在技术方面出现一些错误。 现在,新方法可以测量溶液中的微量钙离子,而没有长期的重力测量方法。

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  Solubility Product Constant
  ::溶溶性产品常量

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  have widely differing solubilities. Sodium chloride has a of about 360 g per liter of water at 25°C. Salts of alkali metals tend to be quite soluble. On the other end of the spectrum, the solubility of zinc hydroxide is only 4.2 × 10 ^-4  g/L of water at the same temperature . Many ionic compounds containing hydroxide are relatively insoluble.
  ::氯化钠在25°C时每升水约360克。碱性金属的盐往往相当溶解。在光谱的另一端,氢氧化锌在同一温度下溶解度仅为4.2×10-4克/升。许多含有氢氧化物的离子化合物相对不溶解。

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  Most ionic compounds that are considered to be insoluble will still dissolve to a small extent in water. These “mostly insoluble” compounds are considered to be strong electrolytes because whatever portion of the that dissolved also dissociates. As an example, silver chloride dissociates to a small extent into silver ions and chloride ions upon being added to water.
  ::被认为是不可溶解的多数离子化合物仍然会在水中小程度上溶解,这些“大多无法溶解的”化合物被认为具有很强的电解层,因为溶解的这些化合物中的任何部分也会分解。 例如,氯化银在水中添加银离子和氯化离子时,会在一定程度上分离成银离子和氯化离子。

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  $$\begin{array}{r}\text{AgCl}(s)\rightleftarrows {\text{Ag}}^{+}(aq)+{\text{Cl}}^{-}(aq)\end{array}$$

  
  ::AGCl +Ag+(aq)+Cl-(aq)

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  The process is written as an equilibrium because the occurs only to a small extent. Therefore, an equilibrium expression can be written for the process. Keep in mind that the solid silver chloride does not have a variable and so is not included in the expression.
  ::进程是写成为平衡, 因为只发生于一个很小的程度上。 因此, 可以为此进程写上均衡表达式 。 请记住, 固态氯化银没有变量, 因此没有包含在表达式中 。

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  $$\begin{array}{r}{K}_{sp}=[{\text{Ag}}^{+}][{\text{Cl}}^{-}]\end{array}$$

  
  ::Ksp= [Ag+][Cl-] Ksp = [Ag+][Cl-]

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  This equilibrium constant is called the solubility product constant ,  $\begin{array}{r}(K_{sp})\end{array}$ and is equal to the mathematical product of the ions each raised to the power of the coefficient of the ion in the dissociation equation.
  ::这个平衡常数被称为溶解性产品常数(Ksp),等于分离方程式中离子系数功率产生的离子的数学产品。

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  The stoichiometry of the formula of the ionic compound dictates the form of the  $\begin{array}{r}{K}_{sp}\end{array}$ expression. For example the formula of calcium phosphate is Ca ₃ (PO ₄ ) ₂ . The dissociation equation and  $\begin{array}{r}{K}_{sp}\end{array}$ expression are shown below:
  ::离子化合物公式的声学度量决定了 Ksp 表达式的形式。 例如,磷酸钙的公式是 Ca3(PO4)2, 分离方程和 Ksp 表达式如下:

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  $$\begin{array}{r}{\text{Ca}}_3({\text{PO}}_4{)}_2(s)\rightleftarrows 3{\text{Ca}}^{2+}(aq)+2{\text{PO}}_4^{3-}(aq)K_{sp}=[{\text{Ca}}^{2+}{]}^3[{\text{PO}}_4^{3-}{]}^2\end{array}$$

  
  ::Ca3(PO4)2(s)3Ca2+(aq)+2PO43-(aq)Ksp=[Ca2+]3[PO43-]2

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  Table lists solubility product constants for some common nearly insoluble ionic compounds.
  ::表格列出了某些常见的几乎无法溶解的离子化合物的溶解性产品常数。

  Solubility Product Constants (25°C)

  Compound	$\begin{array}{r}{K}_{sp}\end{array}$	Compound	$\begin{array}{r}{K}_{sp}\end{array}$
  AgBr	5.0 × 10 -13	CuS	8.0 × 10 -37
  AgCl	1.8 × 10 -10	Fe(OH) 2	7.9 × 10 -16
  Al(OH) 3	3.0 × 10 -34	Mg(OH) 2	7.1 × 10 -12
  BaCO 3	5.0 × 10 -9	PbCl 2	1.7 × 10 -5
  BaSO 4	1.1 × 10 -10	PbCO 3	7.4 × 10 -14
  CaCO 3	4.5 × 10 -9	PbI 2	7.1 × 10 -9
  Ca(OH) 2	6.5 × 10 -6	PbSO 4	6.3 × 10 -7
  Ca 3 (PO 4 ) 2	1.2 × 10 -26	Zn(OH) 2	3.0 × 10 -16
  CaSO 4	2.4 × 10 -5	ZnS	3.0 × 10 -23

   

   

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  Summary
  ::摘要

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  • The solubility product constant is defined.
    ::定义了溶解性产品常数。
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  • Calculations using solubility product constants are illustrated.
    ::说明使用可溶性产品常数进行的计算。

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  Review
  ::回顾

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  1. What does the  $\begin{array}{r}{K}_{sp}\end{array}$ tell us?
     ::KSP告诉我们什么?
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  2. Which of the lead salts listed in the table above is the most soluble?
     ::上表所列铅盐中哪一种最易溶解?
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  3. What is the exponent for an ion in the equation?
     ::等式中离子的出处是什么?