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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.
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| 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). Thus, 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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