Name: kelvin temperature and gas thermometer standards
Uploaded: 2023-04-30T12:29:16.000Z
Duration: 1 min 22 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Chemistry

CHEM.13

CHEM.13.D

Gas Thermometers and the Kelvin Scale

Un termómetro de gas evalúa la temperatura en función de los cambios en la presión o el volumen del gas lleno.
Hay dos tipos de termómetros de gas: de volumen constante y de presión constante, y el termómetro de gas de volumen constante es el más utilizado.
El principio de este termómetro es que, a volumen constante, la presión de un gas aumenta a medida que aumenta la temperatura.
Para calibrar el termómetro de gas, se mide la presión a 0 y 100 grados centígrados.
Estos valores se trazan en una línea recta, que se extrapola para encontrar la temperatura de presión cero.
Esta temperatura es el punto cero de la escala Kelvin. Esta es la escala estándar para la temperatura, ya que la unidad de temperatura del SI es Kelvin.
El cero absoluto es la temperatura más baja posible que refleja idealmente la ausencia total de energía térmica.
En la escala Kelvin, el punto de congelación del agua es 273,15, mientras que el punto de ebullición es 373,15. La diferencia es la misma que en la escala Celsius; Solo el punto cero es diferente.
Por lo tanto, la relación entre las escalas Kelvin y Celsius se puede establecer fácilmente.

<ol>
	<li>OpenStax. (2019). Física Universitaria Vol. 2. [Versión web]. Obtenido de <a href="https://openstax.org/books/university-physics-volume-2/pages/1-2-thermometers-and-temperature-scales">https://openstax.org/books/university-physics-volume-2/pages/1-2-thermometers-and-temperature-scales</a></li>
</ol>

termómetros de gas y la escala kelvin

La definición de temperatura en términos de movimiento molecular sugiere que debería haber una temperatura mínima posible, donde la energía cinética promedio de las moléculas es cero (o el mínimo permitido por la mecánica cuántica). Experimentos confirman la existencia de dicha temperatura, llamada cero absoluto. Una escala de temperatura absoluta es aquella cuyo punto cero es el cero absoluto. Tales escalas son convenientes en la ciencia porque varias magnitudes físicas, como el volumen de un gas ideal, están directamente relacionadas con la temperatura absoluta. La escala Kelvin es la escala de temperatura absoluta que se utiliza comúnmente en la ciencia. La escala Kelvin es parte del sistema SI de unidades, por lo que su definición real es más complicada que la dada anteriormente. Primero, no se define en términos de los puntos de congelación y ebullición del agua, sino en términos del punto triple. El punto triple es la combinación única de temperatura y presión en la cual hielo, agua líquida y vapor de agua pueden coexistir de manera estable. La temperatura del punto triple se define como 273.16 K. Esta definición tiene la ventaja de que aunque la temperatura de congelación y de ebullición del agua dependen de la presión, solo hay una temperatura de punto triple. Aun con puntos bien definidos en la escala, diferentes termómetros dan resultados algo diferentes para otras temperaturas. Por lo tanto, se requiere un termómetro estándar. Los metrologistas han elegido el termómetro de gas de volumen constante para este propósito. Un recipiente de volumen constante lleno de gas es sometido a cambios de temperatura, y la temperatura medida es proporcional al cambio de presión. Los resultados dependen en cierta medida de la elección del gas, pero cuanto menos denso sea el gas en la ampolla, mejores serán los resultados para diferentes gases. Si los resultados se extrapolan a densidad cero, los resultados concuerdan bastante bien, con una presión cero correspondiendo a una temperatura de cero absoluto. Los termómetros de gas de volumen constante son grandes y alcanzan el equilibrio lentamente, por lo que se utilizan principalmente como estándares para calibrar otros termómetros.

Termómetros de gas y la escala Kelvin

La definición de temperatura en términos de movimiento molecular sugiere que debería haber una temperatura más baja posible, donde la energía cinética promedio ...

Education

Educación

JoVE Core

Physics

Física

Unit 1

Unidad 1

Temperature and Heat

Temperatura y calor

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

kelvin temperature and gas thermometer standards

Kelvin temperature is the absolute scale used in science, and it starts at absolute zero. That zero point matches the lowest possible temperature, where molecular motion reaches zero or the minimum allowed by quantum mechanics. Scientists use this scale because some physical quantities, such as the volume of an ideal gas, depend directly on absolute temperature.

The Kelvin scale is part of the SI system of units, so its definition is more precise than simply using water’s freezing and boiling points. Instead, it is tied to the triple point of water. The triple point is the only temperature and pressure combination where ice, liquid water, and water vapor can all coexist. Its temperature is defined as 273.16 K, which is useful because it does not change with pressure the way water’s freezing and boiling points do.

Even with fixed reference points, different thermometers can give slightly different readings for other temperatures. For that reason, scientists need a standard thermometer. Metrologists use the constant-volume gas thermometer for this job. In this device, a gas in a sealed vessel stays at the same volume while temperature changes, and the temperature is found from the change in pressure.

The choice of gas can affect the results a little. However, the less dense the gas in the bulb, the better different gases agree. When the results are extrapolated to zero density, they match well, and zero pressure corresponds to absolute zero. Constant-volume gas thermometers are large and slow to reach equilibrium, so they are mainly used as standards to calibrate other thermometers.

Kelvin Temperature and Gas Thermometer Standards

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Kelvin temperature is the absolute scale used in science, and it starts at absolute zero. That zero point matches the lowest possible temperature, where molecular motion reaches zero or the minimum allowed by quantum mechanics. Scientists use this scale because some physical quantities, such as the volume of an ideal gas, depend directly on absolute temperature. The Kelvin scale is part of the SI system of units, so its definition is more precise than simply using water’s freezing and boiling...

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Learn how the Kelvin scale is tied to absolute zero, the triple point of water, and constant-volume gas thermometers used to calibrate other thermometers.

Kelvin Temperature and Gas Thermometer Standards | JoVE K12

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Kelvin Temperature and Gas Thermometer Standards

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