Kinetic Molecular Theory · 分子动理论
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| kinetic molecular theory/kɪˈnetɪk məˈlekjʊlə ˈθɪəri/ | 分子运动论 | fēn zǐ yùn dòng lùn |
| average kinetic energy/ˈævrɪdʒ kɪˈnetɪk ˈenədʒi/ | 平均动能 | píng jūn dòng néng |
A storm of invisible collisions
- A gas seems still, but its particles are in a frenzy.
- Billions of them zip about and slam into the walls.
- Those collisions are what we feel as pressure.
- A simple model explains gas behaviour from this chaos.
一场看不见的碰撞风暴
- 气体看似静止,它的粒子却处于狂乱之中。
- 亿万个粒子四处飞窜,撞向器壁。
- 那些碰撞正是我们感受到的压强。
- 一个简单的模型从这片混沌中解释气体的行为。
Gas pressure comes from particles colliding with the container . · 气体压力来自粒子撞击容器。
Countless collisions with the walls produce the pressure. · 无数与壁的碰撞产生了压力。
The model's rules
- The kinetic molecular theory 分子运动论 pictures gas particles as tiny and far apart, with no attractions.
- They move in constant, random, straight-line motion.
- Their collisions are elastic, losing no kinetic energy.
模型的规则
- 分子运动论把气体粒子设想为微小、相距很远、无吸引。
- 它们做持续的、随机的、直线的运动。
- 它们的碰撞是弹性的,不损失动能。
In the kinetic molecular theory, collisions are elastic (no kinetic energy is lost). · 在分子动理论中，碰撞是弹性的（不损失动能）。
Elastic collisions conserve the total kinetic energy. · 弹性碰撞守恒总动能。
Temperature is average energy
- Temperature measures the average kinetic energy 平均动能 of the particles.
- Hotter means faster on average.
- At the same temperature, all gases share the same average kinetic energy.
温度就是平均能量
- 温度衡量粒子的平均动能。
- 更热意味着平均更快。
- 在相同温度下,所有气体共享相同的平均动能。
Temperature is a measure of the particles' average... · 温度是粒子平均...的度量。
Temperature tracks the average kinetic energy of the particles. · 温度追踪粒子的平均动能。
Equal temperature means all gases have equal average speed. · 相等温度意味着所有气体具有相等的平均速度。
They share average kinetic energy, not speed -- mass differs. · 它们共享平均动能而非速度——因为质量不同。
A spread of speeds
- The particles do not all move at one speed; they follow a distribution.
- Lighter particles move faster than heavier ones at the same temperature.
- Raising the temperature shifts the whole spread to higher speeds.
速率的分布
- 粒子并非都以同一速率运动;它们服从一个分布。
- 在相同温度下,较轻的粒子比较重的运动得更快。
- 升高温度把整个分布向更高的速率移动。
Pressure from collisions · 碰撞产生的压力
Kinetic theory: gas pressure comes from countless particles colliding with the walls. Shrink the volume and the collisions - and the pressure - increase. · 动理论：气体压力来自无数粒子撞击器壁。缩小体积会使碰撞频率及压力增加。
At the same temperature, a lighter gas moves on average... · 在同一温度下，较轻的气体平均运动...
Same average KE plus smaller mass means a higher speed. · 相同的平均动能加上较小的质量意味着更高的速度。
Raising the temperature shifts the speed distribution toward... · 升高温度使速度分布向...
More thermal energy makes the particles faster on average. · 更多热能使得粒子平均速度更快。
At the same temperature, which moves faster on average, $\text{He}$ or $\text{O}_2$?
- Both have the same average kinetic energy.
- Helium is much lighter, so it must move faster.
在相同温度下,$\text{He}$ 和 $\text{O}_2$ 哪个平均运动得更快?
- 两者有相同的平均动能。
- 氦轻得多,所以它必然运动得更快。
Equal temperature means equal average kinetic energy, not equal speed -- a lighter gas moves faster to match. Temperature depends on speed and mass together. And this theory is the idealization behind $PV = nRT$; real gases stray from it at high pressure and low temperature.
温度相同意味着平均动能相同,而不是速率相同——较轻的气体运动更快来匹配。温度同时取决于速率和质量。而且这个理论是 $PV = nRT$ 背后的理想化;真实气体在高压低温时会偏离它。
The kinetic molecular theory models a gas as tiny, non-attracting particles in constant random motion with elastic collisions. Temperature measures their average kinetic energy, so at one temperature all gases share it -- and a lighter gas moves faster. This model underlies the ideal gas law.
分子运动论把气体建模为微小、无吸引、做持续随机运动、发生弹性碰撞的粒子。温度衡量它们的平均动能,所以在同一温度下所有气体共享它——而较轻的气体运动更快。这个模型是理想气体定律的基础。