Charles:

HCl is a chemical symbol for hydrochloric acid. Concentrated HCl is a saturated solution of chlorine gas in water and has a Normality of 11 - 12. Normality is the chemical definition of an acid's (or bases') ability to release hydrogen (or hydroxide ions) atoms into solution. The higher the numeral the greater the number (equivalents) of ions released and the "stronger" the acid or base. Fisher and other vendors provide dilutions of HCl with water in various strengths. A 0.5 N solution of HCl is (approximately) a 1:24 dilution of 12 N or concentrated HCl with water (1 mL of Conc HCl + 23 mL water). These dilutions can be made by individuals but only if they have access to a chemical fume hood as concentrated HCl is rather noxious. Remember when diluting acids, always add the acid to the water slowly with stirring and in a fume hood. Hope that helped. 
Donna Montague
University of Arkansas for Medical Sciences
Departments of Physiology & Orthopaedic Surgery
4301 W. Markham St. # 505
Little Rock, AR 72205
(501) 603-1239 
-----Original Message-----
From: Charles Read [mailto:csu15397@mail.claytonstate.net] 
Sent: Monday, January 20, 2003 2:36 PM
To: histonet@pathology.swmed.edu
Subject: HCl Question....


Hello!  While reading through the  Fisher Sci. chemical catalog I noticed that in the Hydrochloric Acid section there were many types of HCl, but the only difference was one was labeled 0.5N, another labeled 1N and some were labeled 2N, what does this refer to?  How does it change it's use?  Thanks guys!