first step of a synthesis i found in an old lab text book involved the mixing of 160 mL of 95% sulfuric acid and 105 mL of 75% nitric acid

if i only have, for example, 91% sulfuric acid, or... 69% sulfuric acid, will the synthesis simply not work?

It can but that depends on what you are trying to do.

Textbooks generally use maximum concentrations because chemists simply have a virtual unlimited access to substances/concentrations.

That said, usually it's just for the sake of convenience (using 10ml 96% in place of 30ml 33%, just to speed up the process).

Some synths (TNT for example) won't work unless you're in a certain range of %, since the acid will be too "weak".

You could concentrate it, but leave that alone and learn some basic chem and moles You do not want to bee distilling nitric acid if you do not know wtf is going on. Ask SN he probably has some nice stories to share with us about that

IIRC it forms a couple different azeotropes at different percentages. I don't think it's as simple as distilling it. I believe one would need to add 98% sulfuric acid to a low concentration of nitric acid, and then distill that, but for all that work, you might as well just whip up some 70%+/- via sulfuric+xnitrate salt.

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Well, that depends...

Ignoring ionic disassociation for a sec, let's presume your titrating a base to a nice, balanced salt. Not a "synth," but good enough for this discussion for a sec.

If things are calling for 10ml of 91% sulfuric acid, and you throw in 69ml of 69% sulfuric acid... you will have much, much less H2SO4. This means... much less of the salt is formed, much greater unreacted byproducts are befouling your cleanup, etc...

Now, let's make this even moar bitchin'. Let's say you've got 2 mols of monobromobenzene, 'n 1 mol of paraquinone. Fun, huh? 'n let's say, you've found a solvent which magnesium will actually dissolve in. Probably a wierd-ass freaking solvent, maybe mercury, but we'll presume it works and is inert.

Now... let's say that instead of the volume of 3 mols of solvent at the temperature and pressure of measurement, at 66% concentration, you throw in 3 mols at... 11% concentration...

Normally, you'd think "oh... no problem... just... 1/3rd the yield and a bunch of crap that I hope I'll have to clean up." But... no, no that is not the case.

For starters, any oxygen present is running around contaminating your magnesium while the bromobenzene is floating around this sparse, sparse sea trying to look for what's barely there. There's a risk that you'll get zip for yield, if there's enough oxygen.

Worse still, in the reaction given... the reagent you left unreacted is going to run the risk of brutally attacking the theoretical final product, a triphenyldiol with a partially dearomatized central ring. 'n it's your fault for leaving it in there. So, even if you pull off some yields in spite of degredation at such a low-ass concentration and diluted reaction rate, you could still lose it all.

So, factoring in what we dropped in the first paragraph...

- dilution might retard the reaction while accelerating degradation.

- dilution might prevent concentration required for proper ionization in pH dependent reactions.

...and, the main thing I wrote too many paragraphs about...

- dilution may fuck up your weights and quantities if you don't fucking account for it.

That last one is the big important one, and the rest can be obscenely important, or completely unimportant, depending on the reaction. Know your reaction, and exactlywhat is going on.

...but other times, as long as you standardize to the same molar ratios, it doesn't really fucking matter. All varies from reaction to reaction. Have fun.

Chemistry isn't just mix it all up in there. It's a hard science, and that means every idea is based upon/proven by mathmatics. The math isn't just high school chemistry algebra either. It's calculus. Change the percentage and it's your problem to crunch the numbers.

This is why I'm not looking forward to taking physical chemistry.

That dosn't make sense tho. All chemistry and all biology, hell, everything in this world is based upon physics.

Physics is the prince of sciences; but chemistry is it's awesome brother in law who comes round to your apartment after your sister kicks him out, doesn't pay any rent but always has like a pound of weed in his bag.

hahahahahha fucking loled