Figure P 11.2 provides a particle-level view of a sealed...

Figure $\mathrm{P} 11.2$ provides a particle-level view of a sealed container partially filled with a solution of two miscible liquids: X (blue spheres) and Y (red spheres). Which of the following statements about substances $\mathrm{X}$ and $\mathrm{Y}$ are true? a. $Y$ is the solvent in this solution. b. Pure $Y$ has a higher vapor pressure than pure $X$. c. The presence of $Y$ in the solution lowers the vapor pressure of X. d. If $Y$ were not present, there would be fewer total particles in the gas above the liquid solution. (IMAGE CANNOT COPY)

Figure $\mathrm{P} 11.2$ provides a particle-level view of a sealed container partially filled with a solution of two miscible liquids: X (blue spheres) and Y (red spheres). Which of the following statements about substances $\mathrm{X}$ and $\mathrm{Y}$ are true?
a. $Y$ is the solvent in this solution.
b. Pure $Y$ has a higher vapor pressure than pure $X$.
c. The presence of $Y$ in the solution lowers the vapor pressure of X.
d. If $Y$ were not present, there would be fewer total particles in the gas above the liquid solution.
(IMAGE CANNOT COPY)

Key Concepts

Miscible Liquids

Miscible liquids are substances that can mix together in all proportions without separating into two phases. This concept is important in understanding how two liquid components interact on a molecular level, forming a homogeneous solution where every part of the mixture has the same composition.

Solvent vs. Solute

In a solution, the solvent is typically the component present in the greater amount and serves as the medium in which the solute is dispersed. Recognizing which substance is the solvent is crucial because many properties, such as vapor pressure, are largely determined by the solvent and affected by the addition of a solute.

Vapor Pressure

Vapor pressure is the pressure exerted by the vapor in equilibrium with its liquid (or solid) form at a given temperature. It is a measure of a liquid’s tendency to evaporate; a higher vapor pressure indicates a higher tendency for molecules to escape into the gas phase.

Raoult's Law

Raoult's Law provides a quantitative description of the vapor pressure of a solution, stating that the vapor pressure of a solvent in a solution is proportional to its mole fraction in the liquid phase. This means that adding a nonvolatile component to a solvent lowers the solvent's vapor pressure.

Colligative Properties

Colligative properties are characteristics of solutions that depend on the ratio of the number of solute particles to solvent molecules, rather than the identities of the substances involved. Vapor pressure lowering is one key colligative property, illustrating how even a small amount of solute can affect the physical behavior of the solvent.

Transcript

00:01 This question, i'm not going to redraw the photo, but i'm going to write down the information we should be understanding from it.

00:07 So we have our blue and our red spheres.

00:11 So i'm going to, because we don't have a blue here, i'll just say that x is our blue spheres.

00:16 And i'll write that in purple and y is our red spheres.

00:19 Now, above the liquid in the vapor pressure, we have the same number of molecules of each of.

00:29 So the information we should glean from that is that the vapor pressure of one of these is pretty close to being equal to the vapor pressure of the others.

00:45 Now, in the solution, there's a lot more blue molecules than there are red molecules.

00:51 And so that means that the mole fraction of the y, the red molecules, is a lot smaller.

00:57 So i'll just, i mean, this is literally just me making up numbers.

01:02 So that we have something to concrete to put on, but i'll say that x, the mole fraction here for y, is equal to 0 .1, for example.

01:12 And so then that implies that the mole fraction for the other one, x has to be 0 .9 because they have to add up to 1.

01:19 And so that's really all the information that we need here.

01:22 And so now we can answer everything.

01:24 So which is the solvent? well, the solvent is the one that is in greater proportion.

01:29 So in this case, that's x...

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