Gas laws
International Baccalaureate · IB Diploma · Physics · HL Topic 8 4:18 English narration · English + 中文 subtitles burned in
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A sealed gas container changes pressure when heated.
密封气体容器在加热时压强会发生变化。
Celsius ratios cannot predict the pressure change because the gas model uses absolute temperature 绝对温度.
由于气体模型使用绝对温度，因此摄氏温标比值无法预测压强的变化。
In a gas model, particles move randomly and pressure results from momentum transfer at walls.
在气体模型中，粒子做无规则运动，压力源于粒子与器壁碰撞时的动量传递。
The ideal gas equation connects pressure, volume, amount and absolute temperature.
理想气体方程将压强、体积、物质的量和热力学温度联系起来。
Absolute temperature is temperature on the Kelvin scale.
热力学温度是指以开尔文温标表示的温度。
An ideal gas is a gas model with specified simplifying assumptions.
理想气体是一种具有特定简化假设的气体模型。
At fixed amount and volume, pressure is proportional to Kelvin temperature.
在物质的量和体积固定时，压强与开尔文温度成正比。
At fixed temperature and amount, pressure is inversely proportional to volume.
在温度和物质的量固定时，压强与体积成反比。
State which quantities are fixed before choosing a relationship.
选择关系式前，请明确哪些物理量是固定的。
In the lab: Use approved apparatus with a temperature range and pressure limit set by the teacher.
在实验室中，请使用经批准且温度范围和压力限制由教师设定的仪器。
Allow thermal equilibrium and record pressure against kelvin temperature.
待热平衡建立后，记录压力与开尔文温度的关系。
Never heat an improvised sealed vessel.
切勿加热临时密封的容器。
Known: pressure is 100 kPa at 300 K, with fixed volume and amount.
已知：在300 K时压强为100 kPa，体积和物质的量恒定。
At 330 K, p2 divided by p1 equals T2 divided by T1.
在330 K时，p2除以p1等于T2除以T1。
So p2 equals p1 times T2 divided by T1, which is 100 times 330 divided by 300, equaling 110 kPa.
因此p2等于p1乘以T2除以T1，即100乘以330除以300，结果为110 kPa。
A 30 degrees Celsius rise is a 30 K change, but the temperature ratio must use kelvin.
温度升高30摄氏度相当于变化了30 K，但在计算温度比值时必须使用开尔文温标。
Your turn: At fixed volume, pressure is 120 kPa at 300 K.
轮到你了。 在体积恒定的情况下，300 K 时压强为 120 kPa。
Find pressure at 350 K.
求 350 K 时的压强。
Pause the video and work it out.
请暂停视频，自己算一算。
Check: pressure scales with kelvin temperature: 120 times 350 over 300 is 140 kilopascals.
核对：压强与开尔文温度成正比：120 × 350 ÷ 300 = 140 千帕。
An ideal gas is a model with conditions of validity.
理想气体是一个具有适用条件的模型。
Celsius zero is not zero molecular motion, and internal energy is not determined by pressure alone.
摄氏零度并非分子运动停止，内能也不仅由压强决定。
Not true that a gas pressure ratio can always use Celsius temperatures.
不正确。 气体压强比不能总是使用摄氏温度。
Ratios of temperatures are meaningful only from absolute zero.
温度比只有从绝对零度起算才有意义。
300 kelvin to 350 kelvin is a ratio of 350 over 300; the same temperatures in Celsius, 27 and 77, give 77 over 27, a different and wrong answer.
300 开尔文到 350 开尔文的比为 350 除以 300；同样的温度用摄氏度表示为 27 和 77，得到 77 除以 27，这是一个不同的、错误的答案。
In a gas model, particles move randomly and pressure results from momentum transfer at walls.
在气体模型中，粒子做无规则运动，压强源于粒子与器壁碰撞时的动量传递。
At fixed amount and volume, pressure is proportional to Kelvin temperature.
在物质的量和体积保持不变时，压强与开尔文温度成正比。
Watch for: an ideal gas is a model with conditions of validity.
请注意：理想气体是一个具有适用条件的模型。
At fixed volume, the pressure is 90 kilopascals at 200 kelvin.
在体积固定时，200 K 下的压强为 90 kPa。
Find the pressure at 300 kelvin.
求 300 K 时的压强。
The ratio must use kelvin.
比值必须使用开尔文温标。
The result is a pressure of 135 kilopascals.
结果是压强为135千帕。
Halve the pressure and the volume doubles.
压强减半，体积加倍。
Every point gives the same product of pressure and volume, 6,000, so pressure is inversely proportional to volume at constant temperature.
每个点的压强与体积之积都是6000，所以温度不变时压强与体积成反比。
An ideal gas changes from 300 K, 100 kPa and volume V to 450 K and volume 2V at fixed amount.
一定量的理想气体从 300 K、100 kPa、体积 V 变为 450 K、体积 2V。
Find the pressure. Explain why using only a temperature ratio would fail.
求此时的压强，并说明为什么只用温度比会出错。
The combined relation gives p2 equals p1, times T2 over T1, times V1 over V2, which is 75 kPa.
由综合关系式，p₂ 等于 p₁ 乘以 T₂/T₁ 再乘以 V₁/V₂，即 75 kPa。
The volume also changes, so the fixed-volume formula does not apply.
体积也发生了变化，所以等容公式不适用。
Use absolute temperature.
要使用热力学温度。
Pause and check yourself. Explain each point on screen in your own words, then change one number in the last example and say which assumption must still hold.
暂停一下，自我检查：用自己的话解释屏幕上的每个要点，再改动最后一个例子中的一个数字，说明哪个假设仍然必须成立。