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I would like to know whether milk is acid or base. Is it good for a gastric patient to consume milk?? I would also like to know why hydrochloric acid resolves in water when it is a covalent.
Question Date: 2006-05-04
Answer 1:

Milk is mildly basic; notice how milk curdles when it is mixed with something acid (e.g. orange juice).

All atomic bonds are partially ionic and partially covalent, resulting in compounds having electric dipoles. If two atoms are bonded together that have differing preferences to be negative or to be positive (this is called "electro negativity"), then they will have an electric dipole between the atoms, even if they are still sharing electrons, because the electrons will spend most of their time near the more electronegative atom. Elements on the periodic chart that are above and to the right are more electronegative; thus, the most electronegative element is Fluorine, because none of the inert gasses are chemically reactive at all.

Hydrogen chloride is composed of hydrogen (not electronegative), and chlorine (very electronegative). This, there is a substantial electric dipole between them. Water is composed of hydrogen and oxygen (which is even more electronegative). Hydrochloric acid dissolves in water because the two are polar, so there are interactions between electric charges between them. Once dissolved, the hydrogen is not held to the chlorine that strongly (there is a high ionic component, and chlorine is a large atom), so the bond becomes truly ionic, the hydrogen comes off, and the chlorine is stuck with the extra electron. This is why it is an acid. Alcohol, by contrast, is also polar, again because of a hydrogen-oxygen bond, but the oxygen is a smaller atom and holds onto the hydrogen much more strongly, so it is a much weaker acid.

Answer 2:

This is a very good question. The answer is that when Hydrochloric Acid does dissolve in water, it is like a chemical reaction. It is quite different from when you dissolve sugar in water. Sugar molecules still exist in the water. When you dissolve it in water, HCl is broken up into the ions H+ and Cl-. It is these ions that are stabilized in water, and usually, they can be quite far apart from one another. So the reason that HCl dissolves in water despite being covalent, is that it is willing to break up into ions.

If you dissolved HCl in a solvent such as benzene, it would not break up, and instead would retain its identity as a covalent molecule.

Answer 3:

Just a quick answer: whether people with gastric problems should or should not consume milk has nothing to do with whether it is acidic or basic. When I had an ulcer, drinking milk was the only thing that made me feel better for over a month. However, I was told by my doctor not to drink milk because it is hard to digest. It sits in the stomach for a long time, apparently, and meanwhile your stomach is secreting acid. With my problem, I was secreting too much acid all the time (stress), so having some milk sit in my stomach to "soak it up" really helped. A better solution was to take medication to block acid production, which eventually allowed my stomach to heal.

When milk is fresh it has a pH close to neutral (6.7-6.5). As the milk ages, bacteria begin to grow that produce lactic acid, so the pH of milk will drop (<5.0) as it "sours".

Hydrochloric acid is never pure; it is always a mix of water and hydrogen chloride. So it is the hydrogen chloride (a gas) which is soluble and covalent. Hydrogen chloride (HCl) dissociates in water, which is what allows it to "dissolve". The hydrogen ions (protons) react with water to form hydronium ions (H3O) and the chloride ions are free in solution. Water that is "saturated" with hydrogen chloride gas (as much gas has dissolved as is possible), is about 40% hydrochloric acid.

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