Is the neutralization of hydrochloric acid an exothermic or endothermic reaction?
Neutralizing or even diluting a concentrated acid can be very
exothermic. It can even cause the solution to boil if you are not
careful! This is extremely dangerous!
This is why when diluting concentrated acids (any kind) you
should ADD ACID TO WATER and not the opposite.
See the link below for more information about this important
safety issue in the laboratory due to the exothermic nature of this