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Discussion => Drug safety => Topic started by: DigitalDream on August 20, 2012, 09:58 am

Title: How Would One Calculate the Molarity of A 99.9% Liquid of GBL
Post by: DigitalDream on August 20, 2012, 09:58 am
So yeah as the title says, I have no idea how many moles are in the solution as it only states it's '99.9% GBL'.  I'm speaking of jennifers GBL which I intend on converting to GHB.

No prob calculating conc. for NaOH, and of course I have the Mw of GBL :P but '99.9% GBL' in solution doesn't tell me much about it's concentration.  Any clues?  Or just keep adding GBL to NaOH until pH is 8.0? (that's dirty chemistry though lol)
Title: Re: How Would One Calculate the Molarity of A 99.9% Liquid of GBL
Post by: yasusta on August 20, 2012, 01:49 pm
99.9% means 99.9g of GBL in 100ml of solution (you can figure out the molarity from this information but it's not required)

You know that the number of moles of GBL is going to equal the number of moles of final GHB

n(GBL)=n(GHB)=n(NaOH)  (one to one to one ratio)

Using the MW
86.089g of GBL will make 104.1g of GHB (requires 40g of NaOH)

If you do some cross-multiplying, you can figure out the quantities of anything you wish
Title: Re: How Would One Calculate the Molarity of A 99.9% Liquid of GBL
Post by: DigitalDream on August 20, 2012, 06:14 pm
Hrm, the first line is all I needed (I know chemistry, just having a brain fart, or rather a brain diarrhea)

Are you sure that the % yield in solution = mass of GBL?  You're saying 200mL would have 199.8g of GBL? 
Dunno why but this seems very odd to me, but then again like I said i'm having a brain diarrhea shitstorm atm :P

Thanks for advice though, and not berating me by telling me step by step how to do high school chemistry haha.  I'm a trained biochemist whose currently just being an extreme idiot and i've been outta my field for quite some time.  I'm used to my solutions being depicted in molarity (mol/L) which makes it .. obviously much simpler to determine the # of moles :D

PS: Yes I know that 199.8g of GBL is 2.32mol and that the reaction is equimolar, aka 92.79g of NaOH (Mw = 39.997) is needed.  Damn I feel like an idiot lol, just still tryin to get over '99.9%' = 99.9g ... in ... 100ml ... not 1L?
Title: Re: How Would One Calculate the Molarity of A 99.9% Liquid of GBL
Post by: Miss Sixty on August 20, 2012, 06:30 pm
@yasusta
To get weight of GBL in a solution you need to include density of GBL in your calculations.

@DigitalDream

Calculate weight of GBL in a certain volume, use the equation below and you'll get molarity of the said volume.

grams of GBL/molar mass of GBL = x mol

Title: Re: How Would One Calculate the Molarity of A 99.9% Liquid of GBL
Post by: DigitalDream on August 20, 2012, 06:37 pm
@yasusta
To get weight of GBL in a solution you need to include density of GBL in your calculations.

@DigitalDream

Calculate weight of GBL in a certain volume, use the equation below and you'll get molarity of the said volume.

grams of GBL/molar mass of GBL = x mol

I don't know the gram's of GBL in solution, just that the solution is '99.9% pure GBL'.  I'm referring to this listing:

http://silkroadvb5piz3r.onion/index.php/silkroad/item/6207fd01a9

Apparently it's 'supercute' though, which is crucial in calculating the moles <SARCASM> :P

Thank you too for your help :)  (but i'm still nowhere lol)
Title: Re: How Would One Calculate the Molarity of A 99.9% Liquid of GBL
Post by: Miss Sixty on August 20, 2012, 06:51 pm
amount * density

100 ml * 1.1286 g/ml = 112,86 g

or use 99.9 ml (99.9 ml in 99% v/v solution) to get 112,75 g
Title: Re: How Would One Calculate the Molarity of A 99.9% Liquid of GBL
Post by: DigitalDream on August 20, 2012, 06:51 pm
I guess I could also try not being an idiot (and doing exactly what you said)

GBL has a density of 1.1286 g/mL   ... so 1.1286 g/mL * 200mL = 225.72g

Thus 225.72g / 86.089g/mol = 2.62 moles

Yay for being stupid lol !

... and yeah, you beat me to it lol, thanks !

May as well for posterity sake finish .... Mw NaOH = 39.9971g/mol 

39.9971g/mol * 2.62 mol = 104.869g of NaOH !

------

*drool* 330.35g NaGHB assuming 100% yield (which won't happen, but still 330g !)
Title: Re: How Would One Calculate the Molarity of A 99.9% Liquid of GBL
Post by: thebacon on August 21, 2012, 09:38 am
Something if quoted in % it normally refers to the solute and solution state at room temperature.

eg.(which a biochemist like urself would be more than familiar with :D)
0.9% saline solution = 0.9GRAMS NaCl in 100ml of water
5% dextrose solution = 5grams of glucose in 100ml of water
20% olive oil in cream = 20ML of of olive oil in 100GRAMS of cream

Since both water and GBL are liquid at room temperature, i am more inclined to now believe that it is 99.9ml of GBL in 100ml of total solution.
So yeah you do need density ;D

I just also like you to keep in mind that most densities are quoted for 100% pure substances, as more impurities are added, the densities change. In this case the solution is so close to 100% you can use the quoted density, but it will make a difference when you deviate from purity (eg a 70% solution)
Title: Re: How Would One Calculate the Molarity of A 99.9% Liquid of GBL
Post by: DigitalDream on August 28, 2012, 07:17 pm
Something if quoted in % it normally refers to the solute and solution state at room temperature.

eg.(which a biochemist like urself would be more than familiar with :D)
0.9% saline solution = 0.9GRAMS NaCl in 100ml of water
5% dextrose solution = 5grams of glucose in 100ml of water
20% olive oil in cream = 20ML of of olive oil in 100GRAMS of cream

Since both water and GBL are liquid at room temperature, i am more inclined to now believe that it is 99.9ml of GBL in 100ml of total solution.
So yeah you do need density ;D

I just also like you to keep in mind that most densities are quoted for 100% pure substances, as more impurities are added, the densities change. In this case the solution is so close to 100% you can use the quoted density, but it will make a difference when you deviate from purity (eg a 70% solution)

It's actually the density that you would use to determine the mass of GBL in solution as Miss Sixty pointed out, thanks Miss Sixty.

So 1.128 g/ml x 100ml = 112.8g of GBL in a 99% solution.  If it wasn't 99% you'd need to factor in molarity, but since it's not it's a very easy calculation for which I feel embarrassed not knowing lol.  Thanks again Miss Sixty
Title: Re: How Would One Calculate the Molarity of A 99.9% Liquid of GBL
Post by: Ben on August 30, 2012, 01:54 am
Usually a reference like 99 or 99.9% indicates that you are purchasing the pure chemical, apart from 1 or 0.1% impurities or solvents that remain in the product. You can safely do your calculations based on either mass or volume/density with known values.

If you are considering reacting it to GHB, just consider it to be 100% GHL to begin with. You will need to neutralize the end product anyway, at which point you can compensate fore any excess reagent prseent.
 
Title: Re: How Would One Calculate the Molarity of A 99.9% Liquid of GBL
Post by: flicky42 on August 30, 2012, 03:54 am
You are correct in how you found moles GBL but if I'm not mistaken you mentioned that you are titrated with NaOH? I don't know the molecule of GBL but you need to factor in how many protons you plan on titrating. If the number is 1 than yes all you need is a 1:1 ratio of NaOH to GBL but if its more than you have more calculations to do.