章节大纲

  • A 1000 ml beaker with a test tube inside, illustrating lab glassware for experiments.

    How much equipment do you need for an experiment?
    ::实验需要多少设备?

    You are in charge of setting out the lab equipment for a chemistry . If you have twenty students in the lab (and they will be working in teams of two) and the experiment calls for three beakers and two test tubes, how much glassware do you need to set out? Figuring this out involves a type of balanced equation and the sort of calculations you would do for a .
    ::您负责设置化学实验设备 。 如果您在实验室里有20名学生( 他们将分成两队工作 ) , 实验需要3个烤箱和2个测试管, 您需要设置多少玻璃器件 ? 设计这个设备需要一种平衡的方程和一种计算方法 。

    Everyday Stoichiometry
    ::每天Stoicho测量

    You have learned about chemical equations and the techniques used in order to balance them. Chemists use balanced equations to allow them to manipulate chemical reactions in a quantitative manner. Before we look at a chemical reaction, let’s consider the equation for the ideal ham sandwich.
    ::您已经学会了化学方程式和平衡化学方程式的技术。 化学家们使用平衡方程式来让他们以数量化的方式操控化学反应。 在我们研究化学反应之前,让我们考虑理想火腿三明治的方程式。

    An ideal ham sandwich made with ham, cheese, tomato, pickles, and bread.

    The ideal ham sandwich.
    ::理想的火腿三明治

    Our ham sandwich is composed of 2 slices of ham (H), a slice of cheese (C), a slice of tomato (T), 5 pickles (P), and 2 slices of bread (B). The equation for our sandwich is shown below:
    ::我们的火腿三明治由2片火腿(H)、1片奶酪(C)、1片番茄(T)、5片泡菜(P)和2片面包(B)组成。

    2 H + C + T + 5 P + 2 B → H 2 CTP 5 B 2

    ::2H+C+C+T+5P+2B+2B+H2CTP5B2

    Now let us suppose that you are having some friends over and need to make five ham sandwiches. How much of each sandwich ingredient do you need? You would take the number of each ingredient required for one sandwich (its coefficient in the above equation) and multiply by five. Using ham and cheese as examples and using a conversion factor , we can write:
    ::现在让我们假设你有一些朋友在这里, 需要做五种火腿三明治。 您需要每个三明治配料的多少? 您需要一个三明治配方的每个配方( 其在上述方程中的系数) 乘以5。 使用火腿和奶酪作为例子, 并使用转换系数, 我们可以写 :

    5 H 2 CTP 5 B 2 × 2   H 1   H 2 CTP 5 B 2 = 10   H 5 H 2 CTP 5 B 2 × 1   C 1   H 2 CTP 5 B 2 = 5   C

    ::5H2CTP5B2x2 H1 H2CTP5B2=10 H5H2CTP5B2=10 H5H2CTP5B2x1 C1 H2CTP5B2=5C

    The conversion factors contain the coefficient of each specific ingredient as the numerator and the formula of on sandwich as the denominator. The result is what you would expect. In order to make five ham sandwiches, you would need 10 slices of ham and 5 slices of cheese.
    ::转换系数包含每个特定成分作为分子的系数和三明治作为分母的公式。结果就是预期的结果。要做5个火腿三明治,你就需要10片火腿和5片奶酪。

    This type of calculation demonstrates the use of stoichiometry . Stoichiometry is the calculation of the amount of substances in a chemical reaction from the balanced equation. The sample problem below is another stoichiometry problem involving ingredients of the ideal ham sandwich.
    ::这种类型的计算表明了对异构测量法的使用。斯托伊希测定法是从平衡方程式计算化学反应中物质的数量。下面的抽样问题是另一个涉及理想火腿三明治成分的异构法问题。

    Sample Problem: Ham Sandwich Stoichiometry
    ::抽样问题:哈姆桑威奇

    Kim looks in the refrigerator and finds that she has 8 slices of ham. In order to make as many sandwiches as possible, how many pickles does she need? Use the equation above.
    ::金看着冰箱,发现她有8片火腿。为了做尽可能多的三明治,她需要多少泡菜?使用上面的方程式。

    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

    • have 8 ham slices (H)
      ::有8个火腿切片(H)
    • 2 H = 5 P (conversion factor)
      ::2 H = 5 P(换算系数)

    Unknown
    ::未知

    • How many pickles (P) needed?
      ::需要多少泡菜(P)?

    The coefficients for the two reactants (ingredients) are used to make a conversion factor between ham slices and pickles.
    ::这两种反应物(营养物)的系数用来在火腿切片和泡菜之间设定一个转换系数。

    Step 2: Solve.
    ::步骤2:解决。

    8   H × 5   P 2   H = 20   P

    ::8 H×5 P2 H=20 P

    Since 5 pickles combine with 2 ham slices in each sandwich, 20 pickles are needed to fully combine with 8 ham slices.
    ::因为每份三明治里有5份泡菜和2份火腿切片,需要20份泡菜才能与8份火腿切片完全结合。

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

    The 8 ham slices will make 4 ham sandwiches. With 5 pickles per sandwich, the 20 pickles are used in the 4 sandwiches.
    ::8根火腿切片可以做4个火腿三明治 每只三明治5个泡菜, 20个泡菜就用在4个三明治里

    Summary
    ::摘要

    • An example of everyday stoichiometry is given.
      ::给出了日常的声学测量的一个例子。

    Review
    ::回顾

    1. A smoothie contains 1 banana (B), 4 strawberries (St), 1 container of yogurt (Y), and 3 ice cubes (Ic). W rite a balanced equation to describe the relationship.
      ::滑雪含有1个香蕉(B)、4个草莓(St)、1个酸奶容器(Y)和3个冰块(Ic)。 写一个平衡方程式来描述关系。
    2. Write a conversion factor to show the relationship between the number of ice cubes and the number of smoothies produced.
      ::写入一个转换系数,以显示冰块数量与所产冰雪数量之间的关系。
    3. How many strawberries would you need to make 12 smoothies?
      ::你需要多少草莓才能做12个草莓?