章节大纲

  • 常规

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  • 分离

    A person jogging along a snowy path beside a partially frozen river.

    Have you ever seen trucks pour salt on icy roads?
    ::你见过卡车在冰土路上倒盐吗?

    In many areas, ice on the streets and sidewalks represent a serious walking and driving hazard.  One common approach to the ice is to put some form of deicing salt on the surface.  Materials such as sodium chloride or calcium chloride are frequently employed for this purpose.  In order to be effective, the solid material must first dissolve and break up into the that make up the .
    ::在许多地区,街道和人行道上的冰构成一种严重的步行和驾车危险,对冰层的一种常见做法是将某种形式的脱冰盐放在表面,为此经常使用氯化钠或氯化钙等材料,为了有效,固态材料必须首先溶解并分解成构成该物质的物质。

    Dissociation
    ::分离

    An ionic crystal lattice breaks apart when it is dissolved in water.  Dissociation is the separation of ions that occurs when a solid dissolves.  It is important to be able to write dissociation equations.  Simply undo the crisscross method that you learned when writing chemical formulas of ionic compounds.  The subscripts for the ions in the chemical formulas become the coefficients of the respective ions on the product side of the equation.  Shown below are dissociation equations for NaCl, Ca(NO 3 ) 2 , and (NH 4 ) 3 PO 4 .
    ::溶解于水中的离子晶体板解裂。 分离是指固体溶解时发生的离子分离。 重要的是能够写出分离方程式。 简单取消您在刻写离子化合物化学公式时所学到的晶体交叉法。 化学公式中的离子的下标成为方方方方程式中各自离子的系数。 下面显示的是纳科尔、 卡( NO3) 2 和 ( NH4) 3PO4 的分离方程式。

    NaCl( s ) → Na + ( aq ) + Cl - ( aq )
    ::NaCl Na+(aq) + Cl-(aq)

    Ca(NO 3 ) 2 ( aq ) → Ca 2+ ( aq ) + 2NO 3 - ( aq )
    ::Ca(NO3)(aq) Ca2+(aq) + 2NO3-(aq)

    (NH 4 ) 3 PO 4 ( s ) → 3NH 4 + ( aq ) + PO 4 3- ( aq )
    :伤心NH4)3PO4 + 3NH4+(aq)+ PO43-(aq)

    The formula unit of sodium chloride dissociates into one sodium ion and one chloride ion.  The calcium nitrate formula unit dissociates into one calcium ion and two nitrate ions.  This is because of the 2+ charge of the calcium ion.  Two nitrate ions, each with a 1− charge are required to make the equation balance electrically.  The ammonium phosphate formula unit dissociates into three ammonium ions and one phosphate ion.  Note that the polyatomic ions themselves do not dissociate further, but remain intact.
    ::氯化钠的公式单位分解成一种钠离子和一种氯化离子。硝酸钙的公式单位分解成一种钙离子和两种硝酸离子。这是因为对钙离子的电荷为2+。两种硝酸离子,每两种含1-电荷的硝酸离子需要用电算出方程式平衡。磷酸铵的公式单位分解成三种铵离子和一种磷酸盐离子。注意多元原子离子本身没有进一步分解,但保持不变。

    Do not confuse the subscripts of the atoms within the polyatomic ion for the subscripts that result from the crisscrossing of the charges that make the original compound neutral.  The 3 subscript of the nitrate ion and the 4 subscript of the ammonium ion are part of the polyatomic ion and simply remain as part of its formula after the compound dissociates.  Notice that the compounds are solids ( s ) which then become ions in aqueous solution ( aq ).
    ::不要混淆多原子离子内原子的下标的下标,该下标产生于使原化合物中性化的电荷交错。硝酸盐离子的3下标和铵离子的4下标是多原子离子的一部分,在化合物分解后仅作为配方的一部分留在其中。请注意,化合物是固体,然后成为水溶液中的离子(q)。

    A crystalline pile of white solid substance, illustrating ionic compound dissolution.

    Calcium nitrate is a typical ionic compound. In an aqueous solution it dissociates into calcium ions and nitrate ions.
    ::硝酸钙是一种典型的离子化合物,在水溶液中,它分解成钙离子和硝酸盐离子。

    Nonelectrolytes do not dissociate when forming an aqueous solution.  An equation can still be written that simply shows the solid going into solution.  For the dissolving of sucrose:
    ::非电子解析器在形成水溶液时不会分解。 仍然可以写出一个公式, 简单显示正进入溶液的固态。 对于溶解混凝土 :

    C 12 H 22 O 11 ( s ) → C 12 H 22 O 11 ( aq )
    ::C12H22O11(s) C12H22O11(aq)

     

     

    Summary
    ::摘要

    • Dissociation is the separation of ions that occurs when a solid ionic compound dissolves.
      ::分离是指固体离子化合物溶解时产生的离子分离。
    • Nonionic compounds do not dissociate in water.
      ::非离子化合物在水中不分离。

    Review
    ::回顾

    1. Define dissociation.
      ::定义分离。
    2. Do polyatomic ions dissociate when dissolved in water?
      ::溶解到水中时多原子离子会分解吗?
    3. Write the equation for the dissociation of KBr in water.
      ::写入 KBr 在水中的分离方程式 。
    4. Write the equation for the dissociation of NH 4 Cl in water.
      ::写下水中NH4Cll分离的方程。