Section outline

  • Colorful gas containers arranged in a grid, representing different volumes or types of gases.

    How much gas is there?
    ::有多少气体?

    Avogadro was interested in studying .  He theorized that equal volumes of gases under the same conditions contained the same number of particles.  Other researchers studied how many gas particles were in a specific volume of gas. Eventually, scientists were able to develop the relationship between number of particles and mass using the idea of moles .
    ::Avogadro对研究感兴趣。他推断同一条件下同等数量的气体含有相同数量的颗粒。其他研究人员研究了特定气体量中有多少气体颗粒。最终,科学家们能够利用摩尔概念发展颗粒数量与质量之间的关系。

    Conversions Between Mass and Number of Particles
    ::质量和粒子数量之间的转换

    In " ," you learned how to convert back and forth between moles and the number of representative particles.  Now you have seen how to convert back and forth between moles and mass of a substance in grams.  We can combine the two types of problems into one.  Mass and number of particles are both related to grams.  In order to convert from mass to number of particles or vice-versa, it will first require a conversion to moles.
    ::在 “ ” 中, 你学会了如何在摩尔和具有代表性的粒子数量之间回转和回转。 现在你已经看到如何在摩尔和物质质量之间回转和回转了。 我们可以将两种类型的问题合并为一种。 粒子的数量和质量都与克有关。 为了从质量转换为粒子数量或反之,它首先需要转换为摩尔。

    Flowchart showing relationships between number of particles, moles, and mass in chemistry.

    Conversion from number of particles to mass or from mass to number of particles requires two steps
    ::从粒子数转换成质量或从质量转换成粒子数需要两个步骤。

    Sample Problem: Converting Mass to Particles
    ::问题:将质量转换成粒子

    How many molecules is 20.0 g of chlorine gas, Cl 2 ?
    ::氯气 Cl2 有多少个分子是20.0克的?

    Step 1: List the known quantities and plan the problem.
    ::第1步:列出已知数量并规划问题。

    Known
    ::已知已知

    • Cl 2 = 70.90 g/mol
      ::Cl2 = 70.90克/摩尔
    • 20.0 g Cl 2
      ::20.0克 Cl2

    Unknown
    ::未知

    • number of molecules of Cl 2
      ::Cl2 分子数

    Use two conversion factors .  The first converts grams of Cl 2 to moles.  The second converts moles of Cl 2 to the number of molecules.
    ::使用两个转换因子。第一个将克氯2转换成摩尔。第二个将摩尔2转换成分子数量。

    Step 2: Calculate.
    ::第2步:计算。

    20.0   g   Cl 2 × 1   mol   Cl 2 70.90   g   Cl 2 × 6.02 × 10 23   molecules Cl 2 1   mol   Cl 2 = 1.70 × 10 23   molecules Cl 2

    ::Cl2×6.02×1023分子 Cl21 mol Cl2=1.70×1023分子 Cl2

    The problem is done using two consecutive conversion factors. There is no need to explicitly calculate the moles of Cl 2 .
    ::问题使用两个连续转换系数解决。 不需要明确计算 Cl2 的摩尔。

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

    Since the given mass is less than half of the molar mass of chlorine, the resulting number of molecules is less than half of Avogadro’s number .
    ::由于给定质量不到氯摩尔质量的一半,因此产生的分子数量不到Avogadro数量的一半。

     

     

    Summary
    ::摘要

    • Calculations are illustrated for conversions between mass and number of particles.
      ::对粒子质量和数量之间的转换进行了说明。

    Review
    ::回顾

    1. Why can’t we convert directly from number of particles to grams?
      ::为什么我们不能直接从粒子数转换成克?
    2. How many atoms of chlorine are present in 1.70×10 23 molecules Cl 2 ?
      ::1.70×1023分子中的 Cl2 中有多少原子的氯?
    3. How many molecules of BH 3 are in 14.32 grams BH 3 ?
      ::有多少BH3分子在14.32克BH3中?