What type of imf does ethanol have

In bulk solution the dipoles line up, and this constitutes a quite considerable intermolecular force of attraction that elevates the boiling point. And the result Is the difference in volatility consistent with our argument? What intermolecular forces present in ethanol? May 7, Related questions How do intermolecular forces affect freezing point? Citations are the number of other articles citing this article, calculated by Crossref and updated daily.

Find more information about Crossref citation counts. The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric. Find more information on the Altmetric Attention Score and how the score is calculated. The ability to use representations of molecular structure to predict the macroscopic properties of a substance is central to the development of a robust understanding of chemistry.

Intermolecular forces IMFs play an important role in this process because they provide a mechanism for how and why molecules interact. In this study, we investigate student thinking about IMFs that is, hydrogen bonding, dipole—dipole interactions, and London dispersion forces by asking general chemistry college students to both describe their understanding in writing and to draw representations of IMFs.

Analysis of student drawings shows that most students in our study did not have a stable, coherent understanding of IMFs as interactions between molecules.

That is, their representations varied depending on the IMF. Student written descriptions of intermolecular forces were typically quite ambiguous, meaning that it was not possible to determine from the student description alone whether the student understood IMFs as bonds or interactions.

We believe that in situations where spatial information is crucial, free-form drawn representations are more likely to provide meaningful insight into student thinking. List all types of intermolecular forces that you know of below and please define each.

Please give example s of a compound that would exhibit the intermolecular force s that you listed previously. Be sure to list the intermolecular force s that the compound is representing. What is your current understanding of the terms hydrogen bonding, dipole—dipole interactions, and London dispersion forces? Please draw and label a representation below that clearly indicates where the hydrogen bonding is present for three molecules of CH 3 CH 2 OH.

In the box, please describe, in words, anything you were unable to adequately represent in your drawing. Items 8 and 9 are similarly phrased and ask for representations of dipole—dipole and London dispersion forces, respectively. An example showing the question layout is included in Supporting Information. Figure 1. Figure 2. Figure 3. Student demographic information for each cohort; an example question from the IMFA; all combinations of student text and drawing responses.

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View Author Information. Cite this: J. Article Views Altmetric -. Citations Abstract High Resolution Image. Introduction: The Importance of Intermolecular Forces. Our ultimate goal is to use the data from these investigations to develop evidence-based approaches to teaching and learning that will improve understanding of this important construct. In this study, we focus on student understanding of intermolecular forces IMFs , specifically hydrogen bonding, dipole—dipole interactions, and London dispersion forces LDFs.

As we have previously noted, 2 the pathway that connects a molecular structure to the properties of a substance requires a long chain of inferences. Ideally, a student should be able to construct and then use a structure by understanding that the shape and electron distribution in the molecule determine molecular polarity to make deductions about interactions between molecules intermolecular forces that govern both physical and chemical properties.

Each of these tasks is difficult in itself 2 and connecting them to make predictions about properties is highly demanding for students. In essence, we are asking students to move from using Lewis structures as representations to using them as models with which they can predict and explain properties.

For example, we have shown that even organic students struggle to construct Lewis structures 1 and have proposed that, while a rules-based approach to structure drawing provides a deceptively easy way to teach this skill, if students do not understand why they are learning to draw structures, then the tenets for meaningful learning 7, 8 are not met and students do not connect and reinforce skills that do not seem relevant to them.

This is supported by our findings that, even after organic chemistry, many students do not understand how to use Lewis structures to predict anything other than surface-level features of a molecule.

In another study, 4 we interviewed students about how they used structural representations to predict properties. In this environment, where prompting and further elicitation of student ideas was possible, it became clear that, for many students, structure and properties were not explicitly connected.

Typically, students tended to rely on heuristics and surface-level features of molecules to make predictions rather than using the sequence of inferences that they had been taught. In this study, 4 students usually did not use IMFs as a construct to help them reason about properties such as relative boiling points, even when specifically asked probing questions designed to elicit such ideas.

Although some students used terms such as hydrogen bonding or London dispersion forces, few students used them in anything other than a rote fashion. Prior research involving IMFs has focused specifically on hydrogen bonding —perhaps because of its importance in the properties of water and in biological systems—or more broadly on the general topic of IMFs.

For example, Henderleiter and co-workers interviewed students about their understanding of hydrogen bonds and found that, of the 22 organic students, four of them indicated that the hydrogen bond was the covalent bond between an O and H in the same molecule. If students believe that IMFs are interactions within molecules, this idea must affect their models of phase change. This paper describes an investigation into the external representations that students use to communicate about IMFs.

Rather than hoping to prompt discussion of IMFs in a context with a phenomenon such as predicting relative boiling points as we had done previously and which we now know is unlikely to happen 4 , we wanted to ask students specifically about their understanding of IMFs.

As noted, earlier studies with IMFs have most often used forced-choice instruments. While multiple-choice items and diagnostic two-tier instruments are fast and reliable, it has been shown that students can answer these questions without recourse to appropriate scientific thinking.

Theoretical Perspective. The importance of multimodal learning, that is, providing both visual pictures and verbal words support for student learning, has long been emphasized.

It has been proposed that instructional materials providing both words and pictorial representations are more effective because student understanding can be enhanced by the addition of nonverbal knowledge representations.

Drawing should be particularly helpful in identifying student ideas about spatial information; for example, understanding how they view the relative positions of molecules and the forces that act between them. Similarly, having students write about their understanding can also provide useful insights into student thinking. Certainly both modalities require students to construct answers and thus make their ideas explicit. There are several studies that compare two groups of student responses: those who draw and those who write.

For example, Gobert and Clement compared responses for student who drew diagrams or produced text summaries about plate tectonics.

However, in neither study were students asked to both write and draw so it was not possible to compare a particular students textual explanations and drawings. Our goals with this study were to investigate how both writing and drawing about IMFs can provide us with insight into how students understand this concept. Therefore, students were asked to both construct a representation of an IMF i.

That is, we asked students to use more than one modality to answer questions about IMFs in hopes that it would provide us with a more nuanced picture of their understanding than either writing or drawing alone. While the general chemistry course at this university was traditional in content i. Students also completed online homework assignments using a commercially available homework system Mastering Chemistry The common examinations for these courses were exclusively multiple-choice and, at the end of a full academic year, the American Chemical Society ACS nationally normed general chemistry examination 32 was administered as the final exam.

Students in this course typically score around the 75th percentile on the ACS general chemistry exam. All the students included in this study consented to participate in this research by signing informed consent forms. Demographic information for each cohort is provided in Supporting Information. It was developed based on responses from interviews with general chemistry and organic chemistry students where students discussed how they used structural representations to help them understand phase changes.

Interim versions of the IMFA were piloted in student interviews and revised for clarity where necessary. The final version Box was administered to 68 students in a pilot study and was then used in the studies reported here. Items 1—3 ask students for general examples and explanations of IMFs without any specific prompts.

For example, students are asked to explain what they understand by the general term intermolecular forces, which IMFs they know about, and to provide an example of a substance that would exhibit those IMFs. In items 4—9, students are asked specifically about hydrogen bonding, dipole—dipole and London dispersion forces, both by explaining what they understand by these terms items 4—6 as well as constructing drawings or representations items 7—9 that would show the presence of specific IMFs if present.

Note that students were explicitly asked to draw three molecules and the term three was bolded, since in early iterations of the IMFA many students drew only one molecule.

Ethanol was selected as the target for these items because it is a relatively simple molecule that is capable of exhibiting hydrogen bonding, dipole—dipole, and London dispersion forces LDFs. Students were asked to draw structures of ethanol, but were given structural cues CH 3 CH 2 OH so that most students in this study were able to construct a reasonable recognizable representation. The IMFA was administered to both cohorts of students at the end of their second-semester of general chemistry GC2 to ensure that all students had been exposed to, and tested on, the relevant material.

The IMFA was administered outside of lecture in the laboratory setting which students take concurrently with lecture. Students received participation points for at least attempting to complete the IMFA. None of the instructors for the course were involved in data collection or analysis process. Using this system, we prevented students from returning to any prior items once they moved forward so that students were not able to alter their answers as they progressed through the assessment.

In this study, we focus on the student responses to items 2 and 4—9. Drawings items 7—9 from both Cohorts 1 and 2 were analyzed, and written responses items 2, 4, 5, and 6 were analyzed for Cohort 1. Data Analysis: Drawings Items 7—9. The coding feature in beSocratic was used to code and store important actions or features of the drawing.

The major code categories that emerged for drawings of each type of IMF were: within, between, ambiguous, and not present. If a student clearly indicated that the IMF occurred within a molecule i.

Table 1. If the location of an IMF was not clearly specified i. In rare cases, a student might indicate an IMF as both a bond within a molecule as well as occurring between molecules. Some students indicated in words that they were unsure how to answer the question or represent the structures. For example, a student might indicate that the hydrogen bonded to carbon in the ethanol molecule would hydrogen bond with the oxygen of another ethanol molecule.

However, analyzing drawings for correctness of dipole—dipole and LDFs was more challenging because students may represent charge distribution or fluctuating dipoles in many different ways, or not include indications of the role of charges at all. Data Analysis: Text Responses Items 2, 4—6.

The text responses for item 2 where students were asked in general to identify types of IMFs were combined with the specific items 4—6, since many students wrote more detailed responses in item 2 and simply referred to their prior responses in items 4—6.

For this study, each text response was coded specifically for a discussion of the location of the IMFs. Examples of text responses and the corresponding codes are shown in Table 2. Table 2. Small attractive forces. After discussion, we determined that, while the student did mention dipoles within the molecule, it was not apparent where the student considered the weak force to be located.

Results and Discussion. Of these students, only nine were completely correct in showing the hydrogen bonding interaction between an H bonded to an O in one molecule and an O in another molecule. All but three of the drawings coded as within clearly depicted the IMF as the covalent O—H bond within a molecule of ethanol.

For example, in Table 1 within, dipole—dipole all of the C—H bonds are depicted as dipole—dipole interactions. Representations of LDFs include circling individual atoms such as hydrogen in Table 1 within, LDFs , lone pairs of electrons on oxygen atoms, or bonds.

The IMFA was also administered to a second cohort of general chemistry students Cohort 2 in the following year, and the results are also shown in Figure 1. We attribute the slight improvement to the fact that the instructors in the courses were now aware of our results for Cohort 1 and had emphasized IMFs more than usual in the following year.

High Resolution Image. Similarly only a few students stated explicitly that IMFs occur within a single molecule. None of the students in Cohort 1 explicitly stated that hydrogen bonding occurs within a molecule. Indeed most students failed to make any reference to the location of IMFs at all, meaning that most responses received the ambiguous text code, as shown in Figure 2.

Similarly, many students for example, Rebel provided ambiguous responses for LDFs. We suspect that this response may stem from students hearing their instructors talk about LDFs in a similar fashion. While it is true that all molecules are capable of interacting via LDFs, it is easy to imagine that students may understand this as a property of the molecule rather than of the interactions between molecules.

Interestingly, the written responses about dipole—dipole interactions did not follow the same pattern as those for hydrogen bonding and LDFs. While we do not know the reason why more students wrote about dipole—dipole interactions between molecules, like the responses for H-bonding and LDFs, the responses were somewhat superficial. It may be that the students had learned a definition of dipole—dipole that specifically included the idea that the interaction was between molecules.

One factor that made student written responses difficult to interpret was that students often appeared to use words without understanding their meaning. For example, Rueben, as shown in Table 3 , refers to a molecule of fluorine when discussing hydrogen bonding but he probably meant to describe an atom.

This interchanging of atom and molecule has been in reported previously in work by Cokelez and Dumon. Does the geometry of this molecule cause these bond dipoles to cancel each other? The Review module has a page on polarity. The link on the right will open up this page in a separate window. When you are finished reviewing, closing the window will return you to this page. To understand the intermolecular forces in ethanol C 2 H 5 OH , we must examine its molecular structure.

The structure of ethanol is shown on the right. Will there be dipole-dipole interactions in ethanol? Is ethanol a polar molecule? If you can't determine this, you should work through the review module on polarity.

Like ethyl ether, ethanol is a polar molecule and will experience dipole-dipole interactions. Why are the dipole-dipole forces in ethanol stronger than those in ethyl ether? The especially strong intermolecular forces in ethanol are a result of a special class of dipole-dipole forces called hydrogen bonds. This term is misleading since it does not describe an actual bond. A hydrogen bond is the attraction between a hydrogen bonded to a highly electronegative atom and a lone electron pair on a fluorine, oxygen, or nitrogen atom.

Because the hydrogen atom is very small, the partial positive charge that occurs because of the polarity of the bond between hydrogen and a very electronegative atom is concentrated in a very small volume.

This allows the positive charge to come very close to a lone electron pair on an adjacent molecule and form an especially strong dipole-dipole force.