Sciencemadness Discussion Board

6n hcl??

hankxmen - 27-2-2013 at 00:06

I am tryin to understand the mechanism of the 6n hcl in this text from a wiki article:

At the end of the heating period the reaction mixture is cooled to about 100–110° (at lower temperatures a gelatinous precipitate separates) and is then poured into 150 ml. of water contained in a 1-l. Erlenmeyer flask. An additional 100 ml. of water is used to rinse the reaction flask. The diluted mixture is acidified to Congo red by slow addition of 6N hydrochloric acid as the mixture is stirred vigorously to ensure conversion of any precipitated potassium salt to the free acid. The mixture is then cooled by tap water for at least 30 minutes (Note 2). The white precipitate is collected by suction filtration, transferred to a beaker, and is heated with about 250 ml. of water until the solid has melted (Note 3). As the mixture is cooled, it is stirred vigorously by hand until the oil has resolidified. After the mixture has been cooled again, the precipitated acid is collected by suction filtration, washed with water, and dried (Note 4). The yield of hendecanedioic acid, m.p. 110.5–112° (Note 5), is 28.5–30.6 g. (87–93%).

how does one make 6n hcl

DraconicAcid - 27-2-2013 at 00:12

6N (6 normal) hydrochloric acid refers to 6 mol/L hydrochloric acid. You're making a carboxylic acid, which will not be very water soluble, but it will be acidic- if it loses a proton to form the hydrogen hendecanedioate anion, it will stay in solution. If you keep the solution acidic (pH < 5 or so), it will stay as the acid, and can be collected by filtration.

You would make it by diluting concentrated HCl.

blogfast25 - 27-2-2013 at 06:05

Quote: Originally posted by hankxmen  
I am tryin to understand the mechanism of the 6n hcl in this text from a wiki article:

how does one make 6n hcl


Please don't use 'txt inglish' on this forum, it's supposed to be about science. 6 N HCl it is.

36 % HCl is about 12 N (i.e. 12 M)



[Edited on 27-2-2013 by blogfast25]

ScienceSquirrel - 27-2-2013 at 07:07

I would just mix concentrated hydrochloric acid 50:50 with distilled water, it does not matter if it is 5, 6 or 7 molar or normal.

vmelkon - 2-3-2013 at 19:27

I don't like the N format. It means normalized.
In the case of 6 N HCl, it turns out to be 6 M HCl.

In the case of something that has a double ion, like Na2SO4,
you could make a 12 N Na2SO4 solution (with respect to Na+).
With respect to SO4(2-), it would be 6 N.

Something like H3PO4, could be 3 N with respect to H+ ions and 1 N with respect to PO4(3-) ions.

Hope that gave you an idea of how that system works.

hankxmen - 18-3-2013 at 03:38

1. The open reaction mixture is at least two-thirds immersed in the oil bath to help prevent foaming over and is heated strongly and rapidly in order to drive off water and excess hydrazine hydrate.
2. The condenser is immediately replaced, and the mixture is warmed cautiously until any exothermic reaction is complete and then heated under reflux for 1 hour.
A thermometer is suspended through the condenser by copper wire so that the bulb is in the heated liquid, the stopcock of the take-off attachment is opened, and the mixture is distilled sufficiently slowly so that the froth does not rise out of the flask. When the liquid temperature has reached 205–210° (after about 30 ml. of distillate has been collected), the stopcock in the takeoff is closed, the thermometer is removed, and the mixture is heated under reflux for 3 hours. If the temperature is checked during this heating period, it is usually found to be in the range 190–200°.


1. And 2. obviously mean that the hydrazine has water in it and needs to be evaporated correct?


Thank you for everyones response.
I am very new to oragnic chem.

Blogfast25 What are you refering to txt inglish as?

ScienceSquirrel - 18-3-2013 at 18:15

Quote: Originally posted by vmelkon  
I don't like the N format. It means normalized.
In the case of 6 N HCl, it turns out to be 6 M HCl.

In the case of something that has a double ion, like Na2SO4,
you could make a 12 N Na2SO4 solution (with respect to Na+).
With respect to SO4(2-), it would be 6 N.

Something like H3PO4, could be 3 N with respect to H+ ions and 1 N with respect to PO4(3-) ions.

Hope that gave you an idea of how that system works.


I do not like the Normal system either but it is a legacy syetem that appears in old literature so we have to be aware of it.
It is like feet and inches, Imperial and US gallons, etc. I do not like them as they can be difficult to use but they appear all over the place.
Transferring a beer recipe from US gallons to metric requires a calculator but quarts and bushels are a real pain in the bum!

Magpie - 18-3-2013 at 20:23

I still use the term Normal, or N, when referring to the concentration of reagents used in titration. The reason it's useful is that 10mL of a 1N H2SO4 solution will exactly titrate 10mL of a 1N NaOH solution.

And 10mL of 1N NaOH solution will exactly titrate 10mL of a 1N H3PO4 solution, presuming the right indicator is used, of course.

Normality refers to the number of gram-equivalents in 1 liter of solution.