Name: gas mixtures and their partial pressures
Uploaded: 2023-09-18T17:11:17.000Z
Duration: 1 min 11 s
Channel: JoVE

Considere um gás dentro de um recipiente. A pressão exercida pelo gás é a soma das forças exercidas devido às colisões moleculares entre suas moléculas e a superfície circundante.
Um gás com muitas moléculas exerce uma pressão mais alta do que um gás com um número menor de moléculas no mesmo recipiente. Portanto, a pressão do componente individual é chamada de pressão parcial.
Considere uma mistura de gases ideais em um recipiente em equilíbrio térmico. A pressão total dentro do recipiente é igual à soma das pressões parciais de seus componentes. Essa observação é conhecida como lei de Dalton das pressões parciais.
Recordando a equação ideal do gás e substituindo as pressões parciais dos gases individuais, a pressão total pode ser determinada.
A pressão parcial de um vapor que está em equilíbrio com a fase líquida da mesma substância é chamada de pressão de vapor.
A razão entre a pressão parcial do vapor d'água e a pressão de vapor da água a uma temperatura é conhecida como umidade relativa.

<ol>
	<li>OpenStax. (2019). Física Universitária Vol. 2. [Versão da Web], pág. 37 - 38. Obtido de <a href="https://openstax.org/books/university-physics-volume-2/pages/2-2-pressure-temperature-and-rms-speed">https://openstax.org/books/university-physics-volume-2/pages/2-2-pressure-temperature-and-rms-speed</a></li>
</ol>

lei das pressões parciais de dalton

Dalton's Law of Partial Pressure

A pressão parcial de um gás é uma medida da atividade termodinâmica das moléculas do gás. A pressão que um gás criaria se ocupasse o volume total disponível é chamada de pressão parcial do gás. Se dois ou mais gases são misturados em um recipiente, as moléculas se movem aleatoriamente e colidem umas com as outras, fazendo com que atinjam o equilíbrio térmico. Quando os gases têm a mesma temperatura, suas moléculas têm a mesma energia cinética média. Assim, cada gás obedece à lei dos gases ideais separadamente e exerce, individualmente, a mesma pressão nas paredes de um recipiente. Portanto, em uma mistura de gases, a pressão total no recipiente é a soma das pressões parciais dos gases componentes, assumindo comportamento de gás ideal e ausência de reações químicas entre os componentes. Essa lei é conhecida como lei das pressões parciais de Dalton. A teoria foi estabelecida pelo cientista inglês John Dalton (1766-1844). A lei de Dalton é consistente com o fato de que as pressões se somam, de acordo com o princípio de Pascal. Em uma mistura de gases ideais em equilíbrio térmico, o número de moléculas de cada gás é proporcional à sua pressão parcial.

Outra aplicação importante da pressão parcial é a pressão de vapor, que é a pressão parcial de um vapor na qual ele está em equilíbrio com a fase líquida da mesma substância. Em qualquer temperatura, a pressão parcial da água no ar não pode exceder a pressão de vapor da água nessa temperatura, pois sempre que a pressão parcial atinge a pressão de vapor, a água condensa do ar. O orvalho é um exemplo dessa condensação. A temperatura em que ocorre a condensação para uma amostra de ar é chamada de ponto de orvalho. Essa temperatura é facilmente medida resfriando lentamente uma bola de metal; o ponto de orvalho é a temperatura em que a condensação aparece pela primeira vez na bola.

Lei das Pressões Parciais de Dalton

A pressão parcial de um gás é uma medida da atividade termodinâmica das moléculas do gás. A pressão que um gás criaria se ocupasse ...

Education

JoVE Core

Physics

Física

Unit 1

Unidade 1

The Kinetic Theory of Gases

A Teoria Cinética dos Gases

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

gas mixtures and their partial pressures

Gas mixtures have a total pressure that comes from the partial pressures of each gas. A partial pressure is the pressure one gas would make if it filled the whole container by itself. This idea helps explain how gases behave when they are mixed together.

When two or more gases share a container, their molecules move randomly and collide with one another. If the gases are at the same temperature, they reach thermal equilibrium. Their molecules then have the same average kinetic energy. In that case, each gas follows the ideal gas law separately and pushes on the walls of the container on its own.

The total pressure in the container is the sum of the partial pressures of the component gases. This result is called Dalton's law of partial pressures. It applies when the gases behave like ideal gases and do not react chemically with one another. The law was developed by the English scientist John Dalton, who lived from 1766 to 1844. It also agrees with Pascal's principle, which says that pressures add up.

Partial pressure also helps describe vapor pressure. Vapor pressure is the partial pressure of a vapor when it is in equilibrium with the liquid form of the same substance. In air, the partial pressure of water cannot rise above the vapor pressure of water at that temperature. If it reaches that value, water condenses out of the air. Dew is one common example of this process.

The temperature where condensation begins in a sample of air is called the dew point. One simple way to measure it is to cool a metal ball slowly. The dew point is the temperature at which condensation first appears on the ball.

Gas Mixtures and Their Partial Pressures

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Gas Mixtures and Their Partial Pressures | JoVE K12

physics

JoVE Core - Fisica apresenta a teoria e a aplicação de tópicos fundamentais da física, incluindo cinemática, dinâmica, mecânica dos fluidos, estática, ondas e acústica, com vídeos animados concisos e de fácil compreensão. Além disso, os vídeos de cientistas em ação demonstram a aplicação de conceitos relacionados em experimentos de pesquisa clássica e original realizados nos laboratórios de todo o mundo hoje em dia.

Gas Mixtures and Their Partial Pressures

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