Un líquido que tiene una presión de vapor de equilibrio de 130 mm Hg a 25^∘ C se coloca en un r

Un líquido que tiene una presión de vapor de equilibrio de...

Un líquido que tiene una presión de vapor de equilibrio de $130 \mathrm{~mm} \mathrm{Hg}$ a $25^{\circ} \mathrm{C}$ se coloca en un recipiente de $1 \mathrm{~L} \mathrm{co-}$ moel de la figura 11.20. ¿Qué diferencia de presión indica el manómetro y qué composición tiene el gas en el recipiente en cada una de las condiciones siguientes? (a) Se introducen $200 \mathrm{~mL}$ del liquido en el recipiente y se congelan en el fondo. Luego se extrae el aire del recipiente, se sella éste y se permite que el líquido se caliente hasta $25^{\circ} \mathrm{C}$. (b) Se añaden $200 \mathrm{~mL}$ del liquido al recipiente a $25^{\circ} \mathrm{C}$ y presión atmosférica. Después de unos minutos, el recipiente se sella. (c) El recipiente contiene aire a $1 \mathrm{~atm}$ y $25^{\circ} \mathrm{C}$ y se introducen en él unos cuantos $\mathrm{mL}$ del líquido sin dejar que escape aire. Después de unos minutos, quedan unas cuantas gotas de liquido en el recipiente.

Key Concepts

Vapor Pressure

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid phase at a given temperature. It is a fundamental property of a substance that indicates the tendency of its molecules to escape from the liquid state into the gas phase, and is crucial for understanding evaporation and condensation processes.

Phase Equilibrium

Phase equilibrium describes the state in which different phases (such as liquid and vapor) of a substance exist together at constant temperature and pressure without net change over time. This concept underpins many phenomena, including the establishment of vapor pressure and the conditions required for phase transitions within a closed system.

Gas Mixtures and Partial Pressures

In any gas mixture, the total pressure is the sum of the partial pressures of the individual components, as stated by Dalton's law of partial pressures. Understanding how each component contributes to the overall pressure is essential when analyzing systems where vapor coexists with non-condensable gases or when the composition of the gas phase is altered.

Ideal Gas Law

The ideal gas law relates the pressure, volume, temperature, and amount of a gas (PV = nRT), providing a mathematical framework for predicting how changes in one parameter will affect the others. This concept is fundamental in closed systems where gas expansion or compression, as well as changes in temperature, can alter the pressure.

Pressure Measurement (Manometers)

Manometers are devices used to measure the pressure of gases or liquids, typically through the displacement of a column of liquid. They play a key role in experiments and applications where accurate determination of pressure differences is necessary, such as in studies of vapor-liquid equilibrium and gas mixture analysis.

Transcript

00:01 Okay, i've tried to draw an apparatus here, and i think it did a very nice job.

00:05 We have a liquid that has an equilibrium vapor pressure of 130 tor at 25 degrees c, and we placed it in a one -liter vessel.

00:30 This is one liter.

00:34 We're going to figure out the pressure difference shown on the monometer for each of three conditions.

00:50 And let's do these.

00:54 Letter a.

00:57 In letter a, we put 200 milliliters of liquid into the liquid.

01:03 The flask and we freeze it.

01:12 We evacuate the vessel and seal the vessel.

01:26 Then we warm the whole thing to 25 degrees celsius.

01:35 So at this one, i believe this is pretty simple.

01:39 I'm thinking about this correctly.

01:40 This one will just be 130.

01:48 And let me give just a little bit of an explanation for that.

01:54 We're given that the pressure difference on the monometer.

02:17 Is 130 tor.

02:28 And remember that's 130 millimeters mercury as well.

02:33 The gas in the vessel is essentially 100 % molecules of the substance and the vapor phase.

03:16 And we're basically given that it's going to have 130 millimeters mercury.

03:23 That will be the difference in our monometer reading.

03:46 So what that means if we've got this pushing down with atmospheric pressure and this pushing down, with one, we'll have a pressure here pushing this down in 130.

04:00 So it'll be higher this way...

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