16.19 净电量

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  净电量

  

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  Yes, we need the crowd.
  ::是的,我们需要人群。

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  At sports events around the world, we can see a small number of athletes fiercely competing on the field. They get tired, dirty, and sometimes hurt as they try to win the game. Surrounding them are thousands of spectators watching and cheering. Would the game be different without the spectators? Yes, it definitely would. They provide encouragement to the team and generate enthusiasm. The spectators are not really playing the game, but they are certainly a part of the process.
  ::在世界各地的体育赛事上,我们可以看到少数运动员在田野上激烈竞争。当他们试图赢得比赛时,他们变得疲劳、肮脏,有时受伤。围着他们周围是成千上万的观众在观看和欢呼。如果没有观众,比赛会不同吗?是的,肯定会不同。他们给球队提供鼓励并产生热情。观众并没有真正在玩游戏,但他们肯定是游戏过程的一部分。

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  Net Ionic Equations
  ::净电量

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  We can write a molecular equation for the formation of silver chloride precipitate :
  ::我们可以写一个分子方程 来形成氯化银的沉淀剂:

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  $\begin{array}{r}\text{NaCl}+{\text{AgNO}}_3\to {\text{NaNO}}_3+\text{AgCl}\end{array}$
  ::NaCl+AgNO3+NANO3+AgCl

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  The corresponding ionic equation is:
  ::相应的离子方程式是:

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  $\begin{array}{r}{\text{Na}}^{+}(aq)+{\text{Cl}}^{-}(aq)+{\text{Ag}}^{+}(aq)+{\text{NO}}_3^{-}(aq)\to {\text{Na}}^{+}(aq)+{\text{NO}}_3^{-}(aq)+\text{AgCl}(s)\end{array}$
  ::Na+(aq)+Cl-(aq)+Ag+(aq)+Ag+(aq)+NO3-(aq)+(aq)+NO3-(aq)+AgCl(s)

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  If you look carefully at the ionic equation, you will notice that the sodium and the nitrate ion appear unchanged on both sides of the equation. When the two solutions are mixed, neither the Na ⁺ nor the NO ₃ ⁻ ions participate in the reaction. They can be eliminated from the reaction.
  ::如果您仔细看一看离子方程式, 您就会注意到钠和硝酸盐离子在方程式的两侧都未变。 当两种溶液混合时, 纳+ 和 NO3- 离子都不会参与反应。 它们可以从反应中消除 。

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  $$\begin{array}{r}\cancel{{\text{Na}}^{+}(aq)}+{\text{Cl}}^{-}(aq)+{\text{Ag}}^{+}(aq)+\cancel{{\text{NO}}_3^{-}(aq)}\to \cancel{{\text{Na}}^{+}(aq)}+\cancel{{\text{NO}}_3^{-}(aq)}+\text{AgCl}(s)\end{array}$$

  
  ::Na+(aq)+Cl-(aq)+Ag+(aq)+Ag+(aq)+NO3-(aq)+(aq)+NO3-(aq)+AgCl(s)

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  A spectator ion is an ion that does not take part in the and is found in solution both before and after the reaction. In the above reaction, the sodium ion and the nitrate ion are both spectator ions. The equation can now be written without the spectator ions.
  ::旁观者离子是一种离子,它不参与反应,在反应前后的溶液中都能找到。在上述反应中,钠离子和硝酸离子都是旁观者离子。此等式现在可以在没有旁观者离子的情况下写成。

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

  
  ::Ag+(aq)+Cl+AgCl(aq)+AgCl(s)

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  The net ionic equation is the chemical equation that shows only those , compounds, and ions that are directly involved in the chemical reaction. Notice that in writing the net ionic equation, the positively-charged silver was written first on the reactant side, followed by the negatively-charged chloride . This is somewhat customary because that is the order in which the ions must be written in the silver chloride product. However, it is not absolutely necessary to order the reactants in this way.
  ::净离子方程式是化学方程式,它只显示直接涉及化学反应的化学方程式、化合物和离子。请注意,在写净离子方程式时,正电银先写在反应方程式一边,然后是负电氯化物。这有点习惯性,因为离子必须按顺序写在氯化银产品中。然而,用这种方式命令反应方程式并非绝对必要。

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  Net ionic equations must be balanced by both mass and charge. Balancing by mass means making sure that there are equal numbers of each element. Balancing by charge means making sure that the overall charge is the same on both sides of the equation. In the above equation, the overall charge is zero, or neutral, on both sides of the equation. As a general rule, if you balance the molecular equation properly, the net ionic equation will end up being balanced by both mass and charge.
  ::净离子方程式必须平衡质量和电荷。 以质量制衡意味着确保每个元素的数量相等。 以电荷制衡意味着确保方程式两侧的总电荷相同。 在上述方程式中,总电量在方程式两侧为零或中性。 一般来说,如果分子方程式平衡得当, 净离子方程式最终会以质量和电荷平衡。

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  Sample Problem: Writing and Balancing Net Ionic Equations
  ::问题:写作和平衡净电量等量

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  When aqueous solutions of copper(II) chloride and potassium phosphate are mixed, a precipitate of copper(II) phosphate is formed. Write a balanced net ionic equation for this reaction.
  ::当氯化铜(II)氯化铜和磷酸钾的水溶液混合时,就会形成磷酸铜(II)磷酸铜的沉淀物。

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  Step 1: Plan the problem .
  ::第1步:规划问题。

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  Write and balance the molecular equation first, making sure that all formulas are correct. Then write the ionic equation, showing all aqueous substances as ions. Carry through any coefficients . Finally, eliminate spectator ions and write the net ionic equation.
  ::首先写并平衡分子方程式, 以确保所有公式都正确。 然后写出离子方程式, 显示所有水物质为离子 。 携带任何系数 。 最后, 删除旁观者离子, 并写入纯离子方程式 。

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  Step 2: Solve .
  ::步骤2:解决。

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  Molecular equation:
  ::分子方程:

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  $$\begin{array}{r}3{\text{CuCl}}_2(aq)+2{\text{K}}_3{\text{PO}}_4(aq)\to 6\text{KCl}(aq)+{\text{Cu}}_3({\text{PO}}_4{)}_2(s)\end{array}$$

  
  ::3CuCl2(aq)+2K3PO4(aq)6KL(aq)+Cu3(PO4)2(s)

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  Ionic equation:
  ::音量方程式 :

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  $$\begin{array}{r}3{\text{Cu}}^{2+}(aq)+6{\text{Cl}}^{-}(aq)+6{\text{K}}^{+}(aq)+2{\text{PO}}_4^{3^{-}}(aq)\to 6{\text{K}}^{+}(aq)+6{\text{Cl}}^{-}(aq)+{\text{Cu}}_3({\text{PO}}_4{)}_2(s)\end{array}$$

  
  ::3Cu2+(aq)+6Cl+6Cl+6K+(aq)+2PO43+2(aq)+6K+6Cl+6Cl+(aq)+Cu3(PO4)2(s)

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  Notice that the balancing is carried through when writing the dissociated ions. For example, there are six chloride ions on the reactant side because the coefficient of 3 is multiplied by the subscript of 2 in the copper(II) chloride formula. The spectator ions are K ⁺ and Cl ⁻ and can be eliminated.
  ::注意平衡在写入分离离子时经过。 例如, 反应方有六个氯化离子, 因为3的系数乘以氯化铜( II) 公式中2的下标。 旁观方的离子是 K+ 和 Cl - , 可以删除 。

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  Net ionic equation:
  ::净离子方程式 :

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  $$\begin{array}{r}3{\text{Cu}}^{2+}(aq)+2{\text{PO}}_4^{3^{-}}(aq)\to {\text{Cu}}_3({\text{PO}}_4{)}_2(s)\end{array}$$

  
  ::3Cu2+(aq)+2PO43-(aq)+Cu3(PO4)2(s)

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  Step 3: Think about your result.
  ::步骤3:想想你的结果。

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  For a precipitation reaction, the net ionic equation always shows the two ions that come together to form the precipitate. The equation is balanced by mass and charge.
  ::对于降水反应,净离子方程式总是显示形成沉降物的两个离子。该方程式以质量和电荷来平衡。

   

   

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  Summary
  ::摘要

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  • Net ionic equations are described and an example of writing a net ionic equation is given.
    ::介绍了净离子方程式,并举了写净离子方程式的例子。

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  Review
  ::回顾

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  1. What does the name "spectator ion" mean?
     ::"检测离子"这个名字是什么意思?
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  2. Is there a reaction if no precipitate or gas is formed in an ionic equation?
     ::如果在离子方程式中没有形成沉淀物或气体,是否有反应?
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  3. What do we need to balance in net ionic equations?
     ::在净离子方程式中我们需要平衡什么?