Ask A Scientist Chemistry Archive

name         Destiney M.
status       student
age          11

Question -   Why do acids and bases cause a chemical reaction?
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Hi Destiney!
To answer your question one must define what is an acid and what is a base.  The terms acid and base 
generally speaking apply to 2 groups of compounds with opposing sets of characteristics. Different 
scientists proposed theories to justify the behaviour of these compounds when they get together and 
the reactions that  then occur. Some definitions are more restrictive than others,
and since they were stated in different times, the more recent ones possibly must be the more correct
 one, according to the bulk of knowledge that grows and grows every day.

But all have its merits and  and in their time concurred for the development of science. So I will 
use a very old concept of acid and base to satisfy your curiosity. (remember to be old does not mean 
to be wrong in a mandatory way).

Back in 1884,  a Swedish chemist called Svante Arrhenius proposed definitions for acids and bases 
that are still in common use today.
So acids were the substances that in aqueous solutions:
Turn the indicator dye litmus from blue to red; the bases instead turn the litmus that was red from 
contact with acids to the natural blue color.
Arrehnius proposed that an acid is a substance that in aqueous solution releases hydrogen ion (an 
hydrogen atom with a + charge, that is a proton).
A base in aqueous solution releases hydroxide ion, that is OH with one negative charge.
When both acid and base are in contact dissolved together in water there will be positive hydrogen 
ions and negative hydroxide ions. In these circumstances a neutralization reaction is bound to occur, 
and effectively it does producing water and a different
compound called salt
HA + BOH  = BA  +  H2O
where A holds for a positive ion and B for a negative one.

Hope that answer your question.Later on when you go further in your studies surely you will get 
better explanations
And thanks for asking NEWTON.

Mabel
(Dr. Mabel Rodrigues)
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The general reaction of an acid and base ( in water ) is H(+1) + OH(-1) ----> H2O. The concentration 
of H(+1) and OH(-1) in pure water is only 10^-7 moles /liter so any excess of either will quickly 
react to form H2O.

Vince Calder
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