📚 IGCSE Edexcel Science: Gas Pressure and Temperature (5.7) | 定容下气体压强与温度的关系
Understanding how the pressure of a gas changes with temperature is a key concept in IGCSE Edexcel Science. This topic links the microscopic motion of particles to macroscopic observations such as pressure readings on a gauge.
理解气体压强如何随温度变化是IGCSE Edexcel科学的重要概念。该主题将微观粒子的运动与宏观观测（如压力表上的读数）联系起来。
1. Introduction to Gas Pressure | 气体压强入门
Gas pressure is caused by the collisions of gas particles with the walls of their container. Every impact exerts a tiny force, and the cumulative effect over the surface area creates a measurable pressure.
气体压强是由气体粒子与容器壁碰撞引起的。每一次撞击都会产生微小的力，而在整个表面上的累积效应便形成了可测量的压强。
In a sealed container, the number of gas molecules and the volume are fixed. Therefore, the only factor that can change the pressure is the average kinetic energy of the particles, which is directly related to temperature.
在密封容器中，气体分子数和体积是固定的。因此，唯一能改变压强的因素是粒子的平均动能，而动能直接与温度相关。
2. Kinetic Particle Theory and Pressure | 粒子运动论与压强
According to kinetic theory, gas particles are in constant, random motion. They move in straight lines until they collide with each other or the container walls. These collisions are perfectly elastic, meaning no kinetic energy is lost.
根据运动理论，气体粒子处于不断的无规则运动中。它们沿直线运动，直至彼此或与容器壁碰撞。这些碰撞是完全弹性的，即动能不损失。
The pressure of a gas depends on two factors: the frequency of collisions and the force with which particles hit the walls. Both of these are influenced by the speed of the particles.
气体压强取决于两个因素：碰撞的频率以及粒子撞击器壁时的力度。两者都受粒子速度的影响。
3. Temperature and Kinetic Energy | 温度与动能
Temperature is a measure of the average kinetic energy of the particles in a substance. When the temperature of a gas increases, its particles gain kinetic energy and move faster.
温度是物体中粒子平均动能的量度。当气体温度升高时，其粒子获得动能，运动速度加快。
It is crucial to use the Kelvin temperature scale in gas law calculations because it is an absolute scale, where 0 K represents the point at which particles have minimum kinetic energy. The Celsius scale has arbitrary zero points and cannot be used directly in proportional relationships.
在气体定律计算中必须使用开尔文温标，因为它是一个绝对标度，0 K代表粒子具有最小动能的状态。摄氏温标具有任意零点，不能直接用于比例关系。
T(K) = θ(°C) + 273
4. The Relationship at Constant Volume | 定容下的关系
When a gas is heated in a rigid container, its volume cannot expand. The increased kinetic energy of the particles leads to more frequent and more forceful collisions with the walls. Consequently, the pressure rises.
当气体在刚性容器中加热时，其体积无法膨胀。粒子动能的增加导致与器壁的碰撞更频繁、更猛烈。因此，压强上升。
Conversely, cooling the gas reduces particle speed, decreasing both the frequency and intensity of collisions, which lowers the pressure. This direct relationship is linear when temperature is measured in kelvin.
相反，冷却气体降低了粒子速度，降低了碰撞频率和强度，从而压强下降。当使用开尔文温度时，这种直接关系是线性的。
5. The Pressure Law (Gay-Lussac's Law) | 压力定律（盖-吕萨克定律）
For a fixed mass of gas at constant volume, the pressure exerted by the gas is directly proportional to its absolute temperature. This is expressed by the Pressure Law, sometimes called Gay-Lussac's Law.
对于一定质量和恒定体积的气体，其施加的压强与其绝对温度成正比。这由压力定律（有时称为盖-吕萨克定律）表达。
p ∝ T or p₁/T₁ = p₂/T₂
Here, p represents pressure, T is the temperature in kelvin, and the subscripts 1 and 2 refer to the initial and final states. The volume and the amount of gas must remain unchanged.
这里p代表压强，T是开尔文温度，下标1和2代表初始和最终状态。气体的体积和量必须保持不变。
6. Absolute Zero and the Kelvin Scale | 绝对零度与开尔文温标
Absolute zero, defined as 0 K or −273 °C, is the temperature at which particles have the lowest possible kinetic energy. At this theoretical limit, the pressure of an ideal gas would become zero because the particles would cease to move.
绝对零度定义为0 K或−273 °C，是粒子具有最低可能动能的温度。在这个理论极限下，理想气体的压强将变为零，因为粒子将停止运动。
By plotting pressure against temperature in °C and extrapolating the straight line backwards, all gases intersect the temperature axis at −273 °C. This led to the development of the Kelvin scale, where 0 K is absolute zero and each unit step is the same size as 1 °C.
通过绘制压强与摄氏温度的关系图，并将直线向后外推，所有气体都会在−273 °C处与温度轴相交。这导致了开尔文温标的产生，其中0 K为绝对零度，每单位步长与1 °C相同。
| Temperature in °C | Temperature in K |
|---|---|
| 0 | 273 |
| 100 | 373 |
| −273 | 0 |
| 25 | 298 |
7. Experimental Demonstration | 实验演示
A typical experiment to verify the Pressure Law uses a sealed round-bottom flask connected to a pressure gauge and immersed in a water bath. The flask contains dry air, and its volume remains constant because the flask is rigid.
验证压力定律的典型实验使用一个连接压力表的密封圆底烧瓶，将其浸入水浴中。烧瓶内装有干燥空气，且因为烧瓶是刚性的，体积保持恒定。
The water bath is heated gradually, and the temperature (in °C) and pressure readings are recorded. The temperature is then converted to kelvin. Plotting pressure against kelvin temperature yields a straight line passing through the origin, confirming direct proportionality.
逐渐加热水浴，记录温度（°C）和压力读数。然后将温度转换为开尔文。以压强对开尔文温度作图，得到一条通过原点的直线，证实了正比关系。
It is essential to use precise temperature sensors and allow the apparatus to reach thermal equilibrium at each data point.
必须使用精确的温度传感器，
Published by TutorHao | IGCSE Science Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图