Idea Transcript
Custom Search
Home IHC Store Products Services Knowledge Protocols Forum Gallery Jobs Distributors Advertise Blog Contact
Histology FAQ Staining, Histochemistry and Histotechnology (Frequently Asked Questions) Dr. John A. Kiernan Department of Anatomy and Cell Biology The University of Western Ontario London, Canada
AdChoices
Preparation
HCL
Solution
FAQ Home > Miscellaneous Stuff Dilution of concentrated acids: formula etc. Question. If I want to make a 1N solution of, for example, hydrochloric acid how do I convert the liquid, concentrated HCl into a gram value. The bottle of concentrated HCl says it is a 35-36% solution. Answer. This applies to dilution of all concentrated acids (and also to strong ammonia (ammonium hydroxide) solutions. The percentage on the label is weight/weight, not weight/volume, so you have to take into account the density of the concentrated acid. The formula for making one litre of a particular normality, N, is: 100 X M X N V = ----------- B X P X D where V is the volume of concentrated acid needed, M is is its molecular weight, N is the desired normality, B is the basicity (1 for most common acids; 2 for sulphuric; 3 for phosphoric; 1 for ammonia), P is the percentage by weight in the concentrated acid - the figure on the label, and D is the density of the conc. acid (specific gravity) in grams per ml. No, I didn't work it out myself; it's from Lange's Handbook of Chemistry. If the dilution doesn't need to be very precise, you can assume the following normalities for common concentrated acids: Hydrochloric (36%) 12N Nitric (71%) 16N Sulphuric (96%) 36N (= 18M) Acetic (99%+) 17.4N Formic (90%) 23.4N So to make approximately 0.5N hydrochloric acid, you dilute the conc. HCl 24 times. To make a litre, you'd measure 42 ml of the conc. acid (because 1000/24=41.7) and add it to about 800 ml of water. Stir, and make up to a final volume of 1000 ml. Remember to pour the acid slowly into the water, especially sulphuric acid, which generates a lot of heat when mixed with water. John A. Kiernan,
Department of Anatomy & Cell Biology, The University of Western Ontario, LONDON, Canada N6A 5C1 (kiernan[AT]uwo.ca)
Testing Laboratory
Home | About | Disclaimer | Privacy | Contact | Advertise | Site Map Copyright © 2003-2011 IHC WORLD, LLC. All Rights Reserved.