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  • General

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  • 使用溶性规则预测降水量

    Weather prediction map showing various storm risk levels across the United States.

    Will it rain?
    ::会下雨吗?

    Predicting the weather is tricky business. A thorough examination of a large amount of data is needed to make the daily forecast. Wind patterns, historical data, barometric pressure – these and many other data are fed into computers that then use a set of rules to predict what will happen based on past history.
    ::预测天气是一件棘手的事情。 需要彻底审查大量数据才能做出每日预报。 风势模式、历史数据、气压 — — 这些数据和许多其他数据被输入计算机,然后用一套规则来预测根据过去历史将发生的事情。

    Predicting Precipitates Using Solubility Rules
    ::使用溶性规则预测降水量

    Some combinations of aqueous reactants result in the formation of a solid precipitate as a product. However, some combinations will not produce such a product. If solutions of sodium nitrate and ammonium chloride are mixed, no reaction occurs. One could write a molecular equation showing a , but both products, sodium chloride and ammonium nitrate, are soluble and would remain in the solution as . Every ion is a spectator ion and there is not net ionic equation at all.
    ::水反应剂的某些组合导致形成固体沉淀剂作为产品,但是,有些组合不会产生这种产品。如果硝酸钠和氯化铵的溶液是混合的,就不会发生反应。我们可以写一个分子方程来显示一种,但氯化钠和硝酸铵这两种产品都是可溶的,并且会作为一种产品留在溶液中。每个离子都是一种旁观者离子,根本没有纯离子等式。

    It is useful to be able to predict when a precipitate will occur in a reaction. To do so, you can use a set of guidelines called the rules (see Table ).
    ::能够预测反应中何时会发生突发事件是有益的,为此,你可以使用一套称为规则的准则(见表 )。

    Solubility Rules for in Water
    Soluble Compounds containing the alkali metal ions (Li + , Na + , K + , Rb + , Cs + ) and ammonium ion (NH 4 + )
    Soluble Compounds containing the nitrate ion (NO 3 − ), acetate ion (CH 3 COO − ), chlorate ion (ClO 3 − ), and bicarbonate ion (HCO 3 − )
    Mostly soluble Compounds containing the chloride ion (Cl − ), bromide ion (Br − ), and iodide ion (I − ) -- Exceptions are those of silver (Ag + ), mercury(I) (Hg 2 2+ ), and lead(II) (Pb 2+ ) 
    Mostly soluble Compounds containing the sulfate ion (SO 4 2− ) -- Exceptions are those of silver (Ag + ), calcium (Ca 2+ ), strontium (Sr 2+ ), barium (Ba 2+ ), mercury(I) (Hg 2 2+ ), and lead(II) (Pb 2+ )
    Mostly insoluble Compounds containing the carbonate ion (CO 3 2− ), phosphate ion (PO 4 3− ), chromate ion (CrO 4 2− ), sulfide ion (S 2− ), and silicate ion (SiO 3 2− ) -- Exceptions are those of the alkali and ammonium
    Mostly insoluble Compounds containing the hydroxide ion (OH − ) -- Exceptions are those of the alkali metals and the barium ion (Ba 2+ )

    As an example on how to use the solubility rules, predict if a precipitate will form when solutions of cesium bromide and lead(II) nitrate are mixed.
    ::作为如何使用溶解性规则的一个例子,预测当甲基溴和铅(II)硝酸盐的溶液混杂时,是否将形成一种加速剂。

    Cs + ( a q ) + Br − ( a q ) + Pb 2 + ( a q ) + 2NO 3 − ( a q ) → ?

    ::Cs+(aq)+Br-(aq)+Pb2+(aq)+2NO3-(aq)______?

    The potential precipitates from a double-replacement reaction are cesium nitrate and lead(II) bromide. According to the solubility rules table, cesium nitrate is soluble because all compounds containing the nitrate ion, as well as all compounds containing the alkali metal ions, are soluble. Most compounds containing the bromide ion are soluble, but lead(II) is an exception. Therefore, the cesium and nitrate ions are spectator ions and the lead(II) bromide is a precipitate. The balanced net ionic reaction is:
    ::根据溶性规则表,硝酸铵是可溶解的,因为含有硝酸盐离子的所有化合物,以及含有碱金属离子的所有化合物都是可溶解的。

    Pb 2 + ( a q ) + 2 Br − ( a q ) → PbBr 2 ( s )

    ::Pb2+(aq)+2BR-(aq)+PbBr2(s)

     

     

    Summary
    ::摘要

    • Solubility rules allow prediction of what products will be insoluble in water.
      ::溶解性规则可以预测哪些产品在水中是无法溶解的。

    Review
    ::回顾

    1. Are all alkali metal salts soluble?
      ::碱性金属盐类都可以溶解吗?
    2. What chloride salts are not soluble?
      ::哪些氯化盐不能溶解?
    3. Would you expect sodium silicate to dissolve?
      ::你会期待硅酸钠溶解吗?
    4. Is lead(II) sulfate soluble?
      ::铅(II)硫酸盐可以溶解吗?