![]() You have the oxygen atom and it's bonded to two hydrogen atoms, and the oxygen atom likes to hog the electrons more. In fact, in reality, they would be even moreįar apart than this. So up here you have theĪir, this is the air, these are some air molecules, maybe they're nitrogen molecules. What we have here is a zoom-in of the surface of water. That being said then is it true then, that there is a layer of water in the surface, which creates the surface tension, that is denser than the water in the body? If so, how is this possible? Doesn't this contradict the density principle? This is a principle, so there's no way for a layer of denser water to be floating above a less dense layer of water, the denser water layer will always sink below the less dense layer. If you have a container filled with water and you place more water (or any other object) that is denser than any of the layers of the water you have already in the container, this new water (or object) you placed there, will sink and go deeper into the container. Logically, it follows that the there is an increase in the density of the water that is in the surface right? Then, consider the following: "closely packed" would mean, molecules will be closer to one another, meaning the same amount of molecules but occupying less space. Sal explains the solubility of water here:Ģ:13 Sal said that molecules of water in the surface, since they're not being pulled upwards, but only from the sides and downwards, then these molecules are being able to get a little bit more closely packed. Water is what we call a solvent - it can absorb other substances because the oxygen is connected to the hydrogens by what are called ionic bonds, which leaves the oxygen with a negative charge and the two hydrogens with a positive charge, and these charges can pull other molecules like salt apart. Henry's Law explains gas absorption into water, which involves a bit of chemistry: ![]() Oxygen can be pushed into water so that it is absorbed under pressure - given room to expand, the oxygen comes back out of the water and into the air. Water can also contain other substances through pressure and solubility. Agitation (movement) of the water will increase it's absorption of air. Oxygen can diffuse into water, but this happens very slowly if the water is still. Oxygen in water is bound to two hydrogens, which makes it stable as well - at least as far as connecting more oxygen to them goes. Indeed, the physical properties of higher-molecular-weight alcohols are very similar to those of the corresponding hydrocarbons (Table 15-1).Oxygen in the air is usually in the form of O2, which is stable. As the size of the hydrocarbon groups of alcohols increases, the hydroxyl group accounts for progressively less of the molecular weight, hence water solubility decreases (Figure 15-1). In methanol, the hydroxyl group accounts for almost half of the weight of the molecule, and it is not surprising that the substance is completely soluble in water. The water solubility of the lower-molecular-weight alcohols is pronounced and is understood readily as the result of hydrogen bonding with water molecules: ![]() Alternatively, association through hydrogen bonds may be regarded as effectively raising the molecular weight, thereby reducing volatility (also see Section 1-3). Clearly then, the reason alcohols have higher boiling points than corresponding alkyl halides, ethers, or hydrocarbons is because, for the molecules to vaporize, additional energy is required to break the hydrogen bonds. ![]()
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