Chemistry Bond Polarity Lab: Fill & Download for Free

Without knowing the specifics of your course, it's hard to say, but mechanisms are the key to organic chemistry and they depend on knowledge of bonding, polarity etc. Fortunately this is a topic you can read up on yourself. I learned it too long ago to recommend 'A Mechanistic Introduction To Organic Chemistry ' as it's probably out of print, but ask your lab students for a suggestion.

Ethers have the general structure R-O-R'. Alcohols have the general structure R-O-H. The difference is that an alcohol has a hydrogen instead of an organic group attached to the alkoxy group.That hydrogen is far more reactive than an organic group. It is mildly acidic. I don't mean it will burn your clothes off if you were to get soaked in it (OMG--think of all the naked drunks if that were the case!). But it will react with strong bases like KOH or any of the alkali metals. In fact, we used to use potassium isopropoxide to clean our lab glassware. The alkoxide actually dissolved a thin layer of the glass from beneath the stubborn organic residue and in a day or so all you had to do was rinse the glassware and it came out sparkling.The hydrogen also can participate in hydrogen bonding. Thus alcohols can dissolve more polar molecules. Now that won't directly translate into higher reactivity, but it will allow chemistry between more polar reactants to happen. For example, an alcohol can be oxidized to an aldehyde, ketone, or carboxylic acid depending on its structure. Thos oxidizing agents are generally highly polar.So, there you have it. Alcohols are more reactive because there is an OH instead of an OR, and the OH is more polar and more acidic.

The answer to your question becomes more apparent if we consider all of the hydrogen halides in series.Fluorine is known for its chemically anomalous behavior, which shows up all the time in organic chemistry (and there are many labs dedicated just to exploring fluorine chemistry). While the reasons for this are quite complex, a major contributing factor lies in the fact that fluorine is the most electronegative element and can form hydrogen bonds.A great mnemonic is hydrogen likes to have FON, which refers to the elements it can hydrogen bond with: Fluorine, Oxygen, and Nitrogen.For this reason, HF has the greatest boiling point at 1 atm: 19.5 C.By comparison the boiling points of the other hydrogen halides at 1 atm are:HCl- −85.05 °CHBr- −66.8 °CHI- −35.36 °CAs you have stated, the dipole-dipole interactions are more significant in HCl than in the latter two. Yet, clearly we observe from the empirical data that HCl still has a lower boiling point than the others. Therefore, we can conclude that in the case of the hydrogen halides that do not hydrogen bond, the dominant interaction is not based on dipole-dipole interactions. So, what other noncovalent bonds exist in these in the gaseous phase? As you have stated, we have the van der waals attractions.Larger species have stronger van der waals attractions because they are more polarizable i.e. a fraction of their charge can more easily be localized to a specific spot when it encounters another charge. Iodine is gigantic. An iodine atom is roughly the size of an entire benzene ring, for reference. It is extremely polarizable. Bromine is not as polarizable, and chlorine is less so.Therefore, the answer is in the Van der Waals forces. HI has the highest boiling point because it has the strongest van der waals attractions.You have stated that dipole-dipole attractions are stronger than van der waals attractions. While this is generally true, there are many exceptions. For example, water has hydrogen bonding, which is really just a super strong dipole-dipole interaction. It boils at 100 C. Octane, a hydrocarbon with the formula C8H18, has only van der waals forces. Yet, it boils at 125 C.This figure from Petrucci’s General Chemistry gives a really nice summary:Good luck!