Course: 18.1 反应率 | The Way To Learn

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反应率
Two for the price of one!
::一价两价!

Drag racing is a sport where two cars start from a dead stop and drive as fast as they can down a quarter-mile strip. At the end of the strip are timers that determine both elapsed time (how long did it take for them to cover the quarter mile) and top speed (how fast were they going as they went through the timer chute). Both pieces of data are important. One car may accelerate faster and get ahead that way, while the other care may be slower off the line, but can get up to a higher top speed at the end of the run.
::拖拉赛是一个运动, 两辆汽车从死站开始, 并开得越快越好。拖拉赛的尾端是计时器, 确定时间长度( 需要多长时间才能覆盖四分之一英里) 和最高速度( 他们穿越定时伞的速度有多快 ) 。两组数据都很重要。一辆车可以加快速度, 并越快越好, 另一辆车可以越快越好, 另一辆车可以越快越好, 但是在运行结束时可以达到更高的最高速度。

Chemical Reaction Rate
::化学反应率

vary widely in the speeds with which they occur. Some reactions occur very quickly. If a lighted match is brought in contact with lighter fluid or another flammable , it erupts into flame instantly and burns fast. Other reactions occur very slowly. A container of milk in the refrigerator will be good to drink for weeks before it begins to turn sour. Millions of years were required for dead plants under Earth’s surface to accumulate and eventually turn into fossil fuels such as coal and oil.
::其发生速度各异。有些反应很快发生。如果光火柴与较轻的液体或其他易燃物接触,它会立即爆发成为火焰,燃烧速度很快。其他反应会非常缓慢。冰箱中的牛奶容器在酸化开始之前几周内可以饮用。地球上的死植物需要数百万年才能积累并最终变成煤和石油等化石燃料。

Chemists need to be concerned with the rates at which chemical reactions occur. Rate is another word for speed. If a sprinter takes 11.0 s to run a 100 m dash, his rate or speed is given by the distance traveled divided by the time.
::化学家需要关注化学反应发生的速度。速度是速度的另一个词。如果一个短跑者用11. 0 秒来运行100米的破折线, 他的速率或速度会由时间间隔的距离来决定。

$\begin{aligned} speed = \frac{distance}{time} = \frac{100 m}{11.0 s} = 9.09 m/s \end{aligned}$
$\begin{align*}\text{speed}=\frac{\text{distance}}{\text{time}}=\frac{100 \text{ m}}{11.0 \text{ s}}=9.09 \text{ m/s}\end{align*}$
::时间=100 m11.0 s=9.09 m/s

The sprinter’s average running rate for the race is 9.09 m/s. We say that it is his average rate because he did not run at that speed for the entire race. At the very beginning of the race, while coming from a standstill, his rate must be slower until he is able to get up to his top speed. His top speed must then be greater than 9.09 m/s so that taken over the entire race, the average ends up at 9.09 m/s.
::短跑者的平均赛跑速率是9.09米/秒。我们说这是他的平均赛跑速率,因为他没有以这种速度跑整个赛跑。在赛事一开始,他虽然处于停顿状态,但速度必须放慢,直到他达到最高速度。然后,他的最高速度必须大于9.09米/秒,这样整个赛事的平均速度就会达到9.09米/秒。

Runner.

Chemical reactions can’t be measured in units of meters per second, as that would not make any sense. A reaction rate is the change in of a reactant or product with time. Suppose that a simple reaction were to take place in which a 1.00 M aqueous solution of substance $\begin{align*}A\end{align*}$ was converted to substance $\begin{align*}B\end{align*}$ .
::化学反应无法以每秒米单位来衡量,因为这没有任何意义。反应率是反应器或产品随时间变化。假设发生简单的反应时,A物质水溶液为1.00M的水溶液转化为B物质。

$\begin{aligned} A (a q) \to B (a q) \end{aligned}$
$\begin{align*}A(aq) \ \rightarrow \ B(aq)\end{align*}$
::A(aq) B(aq)

Suppose that after 20.0 seconds, the concentration of $\begin{align*}A\end{align*}$ had dropped from 1.00 M to 0.72 M as $\begin{align*}A\end{align*}$ was slowly being converted to $\begin{align*}B\end{align*}$ . We can express the rate of this reaction as the change in concentration of $\begin{align*}A\end{align*}$ divided by the time.
::假设在20秒后,A的浓度从1.00米下降到0.72米,因为A正在慢慢转换为B。我们可以表示这一反应的速度,因为A的浓度会随时间而变化。

$\begin{aligned} rate = - \frac{Δ [A]}{Δ t} = - \frac{[A]_{final} - [A]_{initial}}{Δ t} \end{aligned}$
$\begin{align*}\text{rate}=-\frac{\Delta [A]}{\Delta t}=-\frac{[A]_{\text{final}}-[A]_{\text{initial}}}{\Delta t}\end{align*}$
::=============================================================================================================================== =================================================================================================================================================================================================================

A bracket around a symbol or formula means the concentration in of that substance. The change in concentration of $\begin{align*}A\end{align*}$ is its final concentration minus its initial concentration. Because the concentration of $\begin{align*}A\end{align*}$ is decreasing over time, the negative sign is used. Thus, the rate for the reaction is positive and the units are molarity per second or M/s.
::符号或公式周围的括号是指该物质的浓度。A的浓度变化是其最终浓度减去初始浓度。由于A的浓度随着时间而下降,因此使用了负符号。因此,反应的速率是正的,单位是每秒或每秒或每秒的摩尔度。

$\begin{aligned} rate = - \frac{0.72 M - 1.00 M}{20.0 s} = - \frac{- 0.28 M}{20.0 s} = 0.014 M/s \end{aligned}$
$\begin{align*}\text{rate}=-\frac{0.72 \text{ M}-1.00 \text{ M}}{20.0 \text{ s}}=-\frac{-0.28 \text{ M}}{20.0 \text{ s}}=0.014 \text{ M/s}\end{align*}$
::0.72 M-1.00 M2.00.28 M2.00.28 S=0.014 M/s

The molarity of $\begin{align*}A\end{align*}$ decreases by an average rate of 0.014 M every second. In summary, the rate of a chemical reaction is measured by the change in concentration over time for a reactant or product. The unit of measurement for a reaction rate is molarity per second (M/s).
::A的摩尔性每秒平均下降0.014米;简言之,化学反应率是用反应剂或产品一段时间内浓度变化来衡量的;反应率的计量单位是每秒的摩尔性(M/s)。

Summary
::摘要

The reaction rate indicates how fast the reaction proceeds.
::反应率表明反应速度有多快。

Review
::回顾

What is another word for rate?
::以什么字表示利率?

What does [ ] stand for?
::代表什么?

What are the units of reaction rate?
::反应率单位是多少?

Section outline

General

反应率

Two for the price of one! ::一价两价!

Chemical Reaction Rate ::化学反应率

Summary ::摘要

Review ::回顾

Two for the price of one!
::一价两价!

Chemical Reaction Rate
::化学反应率

Summary
::摘要

Review
::回顾