David Jenkins
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| posted on 23/6/09 at 12:21 PM |
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Need a chemist's advice
No, not about a nasty skin disease, it's about making up a chemical solution!
I need to make a citric acid solution, which has been specified as "10% by weight". I have a small tub of citric acid in crystaline form,
and a lot of water. Can someone advise how I can combine the two to get the solution I require?
I know three-fifths of f**k all about chemistry...
BTW: this solution is for passivating stainless steel, so it is something to do with Locosts... 
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BenB
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| posted on 23/6/09 at 12:24 PM |
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Easy. Weigh out 10g of citric acid. Combine with 90ml of water. Job done 
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David Jenkins
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| posted on 23/6/09 at 12:30 PM |
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Doh!
Even I can cope with that... 
Cheers.
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andyharding
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| posted on 23/6/09 at 01:46 PM |
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Dunno if it's like other nasty acids I've used in the past but you should always add the acid to the water not the other way around or it
might go bang in your face 
Are you a Mac user or a retard?
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David Jenkins
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| posted on 23/6/09 at 01:48 PM |
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Not a problem with crystals...
Also, citric acid's quite mild in comparison with the other usual suspects like sulphuric or nitric.
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iank
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| posted on 23/6/09 at 02:58 PM |
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Still put the crystals into the liquid. It makes a weak acid that gets stronger as you add them, rather than a strong one that gets weaker if you get
what I mean.
Less chance of splashing as well.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Mark Allanson
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| posted on 23/6/09 at 04:42 PM |
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I don't think it is as simple as 10g crystal to 90ml of water. I seem to remember something about molecular weights being used which is the
total atomic weight of the constituent atoms, eg a mole of oxygen is 16g (atomic weight 16) - but get someone else to confirm as it is a VERY long
time since I learnt any chemistry, they called it alchemy in those days!
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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mads
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| posted on 23/6/09 at 04:54 PM |
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Mark, what you are referring to is to do with concentration in terms of moles.
In the pharmaceutical world, 10% by weight would be 10g of substance A in 100g diluent so for David, as suggested it would be 10g Citric acid (as long
as it is pure and classed as 100%) with 90mL water. (we would class water as 1mL = 1g)
We dont use Wikipedia at work as a reliable source of information but in this instance it is
correct
HTH
We gain knowledge faster than we do wisdom!
Life is not a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in
sideways, thoroughly used, totally worn out and loudly proclaiming... "f*ck, what a trip!"
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