![]() ![]() Join my 2000+ subscribers on my YouTube Channel for new A Level Chemistry video lessons every week. Please LIKE this video and SHARE it with your friends! Topic: Intermolecular Forces, Physical Chemistry, A Level Chemistry, Singaporeīack to other previous Physical Chemistry Video Lessons.įound this A Level Chemistry video useful? Since H-O bond is more polar than H-N bond, the hydrogen bonds between ethanol molecules will be stronger than hydrogen bonds between ethylamine molecules, hence boiling point of ethanol will be higher.įor the detailed step-by-step discussion on how to apply factors affecting hydrogen bonds, check out this video! Therefore we have to look at polarity to compare their boiling points. In this case both ethylamine and ethanol can form a maximum of 3 hydrogen bonds each, hence their extensiveness is the same. Remember extensiveness is the more important factor so we have to compare extensiveness first. Let's compare boiling point of ethylamine and ethanol. H-N bond is the least polar hence hydrogen bond between molecules that contain H-N bonds will be the weakest. H-F bond is the most polar hence hydrogen bond between HF molecules will be the strongest. When extensiveness is the same, then we can compare polarity of H-F, H-O and H-N bond to deduce the strength of hydrogen bonds. We can determine that ethanol can form a maximum of 3 hydrogen bond only, hence hydrogen bond is least extensive, least amount of energy required to overcome and melting point is lowest.Įthanedioic acid can form a maximum of 10 hydrogen bonds which is the most extensive, greatest amount of energy required to overcome hence it has the highest melting point. We can determine the maximum number of hydrogen bonds formed for each molecule by drawing out their lewis structures. Let's compare the melting points of ethanol, ethanoic acid and ethanedioic acid. Let's go through the factors affecting Hydrogen bond in this video, which are extensiveness and polarity.Ī molecule that can form more hydrogen bonds with more neighboring molecules will have more extensive hydrogen bonds, hence more energy is required to break more hydrogen bonds per molecule, and the melting/boiling point is higher.Įxtensiveness is related to the maximum number of hydrogen bonds a molecule can form with its neighbours. Hydrogen bond between polar molecules that have H-F, H-O or H-N bonds permanent dipole-permanent dipole attraction between polar molecules instantaneous dipole-induced dipole attraction (or dispersion forces or Van Der Waals forces) between non-polar molecules There are 3 types of intermolecular forces namely: We used these experimental observations to develop a model of phase separation in aqueous media.Simple molecules have weak forces of attraction between them hence their melting and boiling points tend to be much lower as compared to other substances such as metals, ionic compounds and giant molecules. These estimates indicate that abrupt changes in hydrogen bond arrangement take place at concentrations below the threshold of macroscopic phase separation. Best Match Video Recommendation: Solved by verified expert We don’t have your requested question, but here is a suggested video that might help. Through OH-stretch band analysis, we obtain quantitative estimates of the relative fractions of four subpopulations of water structures coexisting in aqueous solutions. Give an example AI Recommended Answer: Step 1/2 Covalent polar bonds are formed when two atoms that have Step 2/2 a partial or complete positive or negative charge join together. Such mesoscopic changes are paralleled by changes in water structure as evidenced by Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopic analysis of OH-stretch bands. These agglomerates increase in size with increasing polymer concentrations prior to visual phase separation. Dynamic light scattering (DLS) analysis indicates the formation of mesoscopic polymer agglomerates in these systems. This work presents the first experimental evidence that mesoscopic changes precede visually detected macroscopic phase separation in aqueous mixtures of two polymers and a single polymer and salt. The mechanism of this process can be examined using simple aqueous mixtures of two or more solutes, which are able to phase separate at specific concentration thresholds. Liquid-liquid phase separation underlies the formation of membrane-less organelles inside living cells. ![]()
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