The graph in Figure P11.4 describes the volume of distillate...

Name: Problem 4, Chapter 11: Chemistry The Science in Context
Uploaded: 2020-05-06T17:58:38-08:00
Duration: 4 min 20 s
Channel: Allea Cauilan
Description: The graph in Figure P11.4 describes the volume of distillate collected during the fractional distillation of a liquid. Answer the following questions about the process: (a) Is the sample a pure liquid or a mixture? (b) If it is a mixture: (i) how many components are in the mixture? (ii) What are the relative ratios of the volumes in the mixture? (iii) What are their approximate boiling points?

The graph in Figure P11.4 describes the volume of distillate collected during the fractional distillation of a liquid. Answer the following questions about the process: (a) Is the sample a pure liquid or a mixture? (b) If it is a mixture: (i) how many components are in the mixture? (ii) What are the relative ratios of the volumes in the mixture? (iii) What are their approximate boiling points?

The graph in Figure P11.4 describes the volume of distillate collected during the fractional distillation of a liquid. Answer the following questions about the process: (a) Is the sample a pure liquid or a mixture? (b) If it is a mixture:
(i) how many components are in the mixture? (ii) What are the relative ratios of the volumes in the mixture? (iii) What are their approximate boiling points?

Key Concepts

Fractional Distillation

Fractional distillation is a separation technique used to separate mixtures based on the differences in the boiling points of the individual components. It involves repeated vaporization-condensation cycles that enhance the separation of components, making it possible to collect distinct fractions corresponding to different boiling points.

Pure Substance vs Mixture

Understanding the difference between a pure substance and a mixture is fundamental. A pure substance has a single, uniform composition and a specific boiling point, whereas a mixture consists of two or more components that can be separated, often exhibiting multiple boiling points during distillation.

Graphical Analysis of Distillation Data

Interpreting a graph of collected distillate volume over time (or temperature) is an important skill in chemistry. The shape of the curve, as well as distinct segments or plateaus, can reveal the presence of different components in a mixture, indicate the relative amounts of each, and help approximate their respective boiling points.

Boiling Point Separation

Boiling points are critical intrinsic properties used to separate components in a mixture via distillation. During the process, components vaporize at their unique boiling points, allowing for their sequential condensation and collection, which is key for identifying each component in the mixture.

Relative Composition Analysis

Determining the relative ratios of components in a mixture involves analyzing the volume or mass of the collected fractions. This analysis, often derived from the integrated graphical data, helps in estimating the proportion of each component present in the mixture.

Transcript

00:01 Okay, so this is problem 11 .4 in the chemistry, the science, and text book, and this is the end of chapter 11, okay? and so it gives us this graph, and it asks a few questions about the graph, okay? and so the graph, when we look at it, it's immediately a distalation.

00:22 We should recognize this is a distillation.

00:24 Okay, it tells us this is a fractional distillation of a certain liquid.

00:27 And with distillation, if you have a pure liquid, what you're going to see is that it's essentially you're going to reach the temperature that pure liquid vaporizes, right? so the boiling point of that pure liquid.

00:45 And you're going to see a straight line at that boiling point because remember, during phase changes when a liquid goes to gas space, there is no change in temperature.

00:54 Okay.

00:54 And you'll just see that there's an increase in the volume of that distillate as you're collecting the vapor.

01:00 Okay, but in this case we have three steps.

01:04 One, two, three.

01:05 Okay, so that answers our first question.

01:08 Is this a mixture? yes, absolutely.

01:10 Okay.

01:10 Because it was pure, we would just see an increase to a certain temperature and then a flat line at that boiling point, okay, as the volume increases for that compound.

01:24 Okay? and then you would see it stop, and that would be it, once you run out of a pure substance.

01:30 But in this case, it's not pure substance.

01:32 Okay, so this is a mixture, and we see that because we have three separate steps.

01:38 Okay.

01:39 And so how many components are there? well, i just answer that.

01:41 There are three, right? we see that we reach 80 degrees celsius, and we start collecting a certain volume of distillate.

01:50 Okay, so that means that there's one compound where its boiling point is around 80.

01:55 Then we run out of that compound and then we increase the temperature to around 95.

02:01 And then that is a boiling point of the second one and it starts to distillate out, meaning that it goes into the gas phase and we collect it as distillate.

02:10 And so we have a certain volume of that.

02:13 And then once we run out of that compound, we have to increase the temperature again to 130 to vaporize that last compound...

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