Acid and Base Fundamentals
Name: Sharaybia J.
Date: May 2008
As a parent, what should I know about acids and
bases? What does an acid do? What does a base do? If you make a
reaction, what will come about?
I am assuming that your question is about safety issues.
The difficulty in trying to answer your question is that there is quite a
wide range of acids and bases that a normal child can encounter in the home
or elsewhere. Vinegar and fruit juices have acid in them. Antacid tablets
and baking soda/baking powder are basic. Most of these substances when used
appropriately are benign or even quite helpful.
On the other hand, there may be some products in your house that are acidic
or basic and can be quite damaging if in contact with skin/eyes or ingested.
Many cleansers are either acidic or basic and can be harmful. The reason such
strong or concentrated acids and bases are harmful can come from at least
three different issues: (a) they are very good solvents - what makes them good
cleansers also makes them dangerous to the skin (which can partially dissolve,
cause irritation, or remove oils and dry them), (b) they are very good
oxidizers - in essence, can react with parts of the body and convert them to
some other substance, (c) they produce quite a bit of heat when they react,
and the heat in itself can do damage.
Last, there are many reports of homeowners who think that mixing different
cleansers will make them work better. This is dangerous because some cleansers
are acids, while others are bases. Not only will mixing such different cleansers
make them less effective, they can also produce much heat and gas. Many people
have been injured by the heat or gases that are produced in such uninformed
Greg (Roberto Gregorius)
Before we can answer what does an acid do, you need to have some
understanding of what an acid IS.
Water is H2O (Usually the 2 is written smaller and below the line, but
I can't do that in plain text)
We could also think of water as an H and an OH - still 2 H's and one O,
H being Hydrogen, and O being Oxygen
The H takes on a + (positive ) charge, while the OH takes on a -
(negative ) charge, because the OH takes an electron from the H. (I hope
you are still with me here!) The H+ cause the solution to act as an
acid, and the OH- causes it to act as a base(or it can also be called an
alkali) In pure water, there will always be the same number of H+'s as
OH-'s so water is neutral - neither acid or base.
Some metals are able to take the H away from the water - and turn them
into Hydrogen gas. This leaves behind the metal now with a + charge,
because it gave an electron to the H+ to make it into hydrogen gas. At
the same time, there are a LOT of left over OH- from the water. This
means that metals produce bases, which are called Metal Hydroxide, such
as Sodium Hydroxide, which is a VERY strong base, and you might use it
to clear drains or wash ovens. (And that is because Fat is a weak acid!!!)
Many non-metals are able to react with water in such a way that they
bind up the OH- and leave a lot of H+ floating around. These solutions
will be acidic. Hydrogen Sulfate dissolves in water to produce lots of
SO4- and lots of H+ Hydrogen Sulfate is usually called sulphuric acid.
Similarly, Hydrogen Chloride can produce lots of H+ (and Cl- ) so HCl is
usually called Hydrochloric acid.
Now here is the kicker - when a strong base and a strong acid are
allowed to react together (carefully we hope - these reactions can be
violent!!) then the result is called a salt.
Hydrochloric Acid HCl plus Sodium Hydroxide NaOH produces water
and Sodium Chloride - which is common sea salt. In chemical notation
we write -
HCl -->H+ + Cl- NaOH --> Na+ + OH-
H+ + Cl- + OH- + Na+ --> HOH + NaCl
( The --> is an
arrow and is read as 'forms' )
Sulfuric Acid + Magnesium Hydroxide --> Water and Magnesium Sulfate
H2SO4 + Mg(OH)2 --> 2H+ + SO4- + Mg++ + 2 OH- --> 2HOH + MgSO4
(that one is a bit more complicated because there are 2 H+'s and 2
These things I have mentioned so far are considered STRONG acids and
bases, because they produce LOTS of H+'s for acid, or LOTS of OH- for
There are MANY MANY MANY substances which are able to produce SOME H+'s
or a FEW H+'s These are less strong, or weak acids. Vinegar is a
medium acid, blood is a weak acid, rain that falls through polluted air
is a weak acid, and as mentioned, fats are weak acids (very very weak as
it turns out).
Likewise, there are MANY MANY MANY substances which are weak bases -
ammonia, spit and limestone (yes the rock) are all weak bases.
Acids and bases are chemical opposites, so something that is an acid
will react with a base and they will both be neutralised. That is why
Sodium Hydroxide is able to dissolve fat, and why acid rain is able to
dissolve limestone (You knew there was a reason for putting those in
didn't you )
Most substances you come across in normal day to day activities will
fall into one category or the other - there are not very many substances
that are completely neutral.
I hope this has been a little bit useful, and not too technical, but you
have entered into a realm of heavy duty chemistry, and it is very hard
to give any explanation without going into details.
By the way - if you react Caustic Soda (Sodium Hydroxide) with a Fat
(Tallow or Stearic Acid) you will end up with something called Sodium
Tallowate or Sodium Stearate. Have a look at the ingredients list on the
side of your soap package, or bottle of handwash and you may well find
Sodium Tallowate or Sodium Stearate as one of the ingredients. Sodium
Tallowate and Sodium Stearate are soap!!!!
Tennant Creek High School
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Update: June 2012