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Author: Subject: Methylamine question
carbon85
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[*] posted on 14-6-2018 at 23:17
Methylamine question


I require a quantity of 30% Methylamine solution in water how much MeNH2 hydrochloride per amount of NaOH is needed to completely convert the hydrochloride salt to dissolved gas i need 100ml of a 30% solution in total

Thank you in advance

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Bert
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16-6-2018 at 00:53
woelen
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[*] posted on 16-6-2018 at 10:52


In order to solve such questions, you need to know the density of a 30% solution, but in this case it is fairly safe to assume a density of 1 g/ml, without being too far off. If you want to be very precise, then find a lookup table with densities of solutions of CH3NH2 for different concentrations.

So, you need to make 30 grams of CH3NH2 if you want 100 grams (which is appr. 100 ml, probably slightly more) of this 30% solution.

Your reaction is: CH3NH2.HCl + NaOH --> CH3NH2 + NaCl + H2O

You need 30 grams of CH3NH2, which is 0.9660 mole of CH3NH2. According to the reaction equation, you also need 0.9660 mole of NaOH and 0.9660 mole of CH3NH2.HCl, which are 38.636 grams of NaOH and 65.22 grams of CH3NH2.HCl.

Making the 30% solution of CH3NH2 requires you to drive off the gas from the reaction mixture and dissolve this in clean water. In practice you need to proceed by dissolving 65 grams of CH3NH2.HCl in water and add excess NaOH to this (I would add the solid). Then you need to heat to boiling to drive off all gas and have to lead this through cold (and chilled) water. Start with 70 ml of water.

Using the solution straight away will not be very satisfying. You will not get a 30% concentration with all the dissolved salt.





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[*] posted on 16-6-2018 at 11:08


That covers it thank you for the in depth explanation my maths are terrible
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[*] posted on 16-6-2018 at 11:13


Don't answer homework questions. Redirect to educational materials.

And don't spoon feed on questions about drug precursors.




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[*] posted on 16-6-2018 at 15:18


BTW an interesting-if-you -have-sodium diazomethane synthesis OS 25, 28 (1945)/CV3 244 (from mesityl oxide) gives directions for 2.1 moles of 30% solution, to be used without removing the salt.



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[*] posted on 17-6-2018 at 10:07


Quote: Originally posted by PirateDocBrown  
Don't answer homework questions. Redirect to educational materials.

And don't spoon feed on questions about drug precursors.
Do not immediately think the most negative of other people. This request differs from the requests about P2P and MDMA synthesis we sometimes see. Let every one decide for himself/herself whether to answer or not.

[Edited on 17-6-18 by woelen]




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