Making X% Y(sol) from >X% Y(sol) ?

[gatecrasher]

Lets say I wanted to make 15 grams of 10% solution of HNO3 from 70% Nitric Acid.

How many grams would I need to put in of the 70% HNO3 to H2O????
Meaning how many grams of H2O and how many grams of the 70% HNO3????

(Obviously this question can be relevant to any other solution, so I changed the title to make it more general...)

<small>[ March 07, 2003, 02:22 PM: Message edited by: Mr Cool ]</small>

[PEROMAN]

You need 2.14g of 70%HNO3 + 12.86g wasser :D

<small>[ March 07, 2003, 02:23 PM: Message edited by: Mr Cool ]</small>

[Arthis]

How does the moderating system work then ? Other mods can't ban or so ? (hell I know it pretty off-topic question but since the topic is dumb... )

[Mr Cool]

Arthis, the moderating system works thusly:

Lamer posts, lamer is seen, lamer is gone :D . That's all you need to know.

As it happens, I think we're experimenting with being nice at the moment. I can't say that I'm a fan of all this kewl-hugging, but we'll see how it goes. Therefore I won't do anything about this topic.
It is actually quite a useful question, syntheses will often ask for X% of Y_(sol), when you have &gt;X%.
What you need to do is work out how much Y is in 100g of your solution, then divide this by the % needed, multiply the number by 100, then subtract 100 (if you started by working with 100g). This will give you the mass of solvent you need to add to 100g of your starting solution to get a given percentage.

eg, you have 70% HNO₃, you need 10%.

100g of 70% HNO₃ contains 70g of HNO₃.
70/10 = 7.
7*100 = 700.
700 - 100 = 600.

Therefore 600g of dH₂O must be added. This will give you 700g of solution, containing 70g of HNO₃, therefore it will be 10% w/w.

<small>[ March 07, 2003, 02:30 PM: Message edited by: Mr Cool ]</small>

[gatecrasher]

MR COOL,

THANKS FOR THE REPLY.

BUT I AM A LAMER, I NEED IT MORE SIMPLER!!

AND WHAT DID I DO WRONG? DO I HAVE MY HEAD UP MY ASS?

<small>[ March 07, 2003, 02:25 PM: Message edited by: Mr Cool ]</small>

[PEROMAN]

Gatecrasher ! Why do you ask 1 question several times???
I have already answered it (look my previous reply)
you need 2.14g of 70%HNO3 + 12.86g water !!!

You can count it easily :
As Mr.Cool said , you need 1 weight part of 70%HNO3 per 6 weight parts of water , and you get 7 weight parts of 10%HNO3

7x = 15
x = 2.14
6x = 12.86

Learn mathematics !

[frogfot]

Since this topic is still on I thoat to ask if anybody is interested in dencity data of aqueus HNO₃ (and H₂SO₄)?
"Handbook of chemistry and physics" got nice tables on this (1% resolution 5 digits accuracy), I can scan this, again, if anybody is interested.

[gatecrasher]

Fine, I'll just boot MYSELF out!!! This is a Communist forum and who needs it GOOD BYE!!!!

--------------------------------
hehe, he's not going to find any better! so long butt sucker!

<small>[ March 07, 2003, 05:33 PM: Message edited by: kingspaz ]</small>

[Mr Cool]

NBK isn't the only one with banning powers you know. He just likes to make a spectacle out of it, other times the lamers are gone before most people are even aware of their existence. No fuss, they just vanish. But like I said, I think we're being nice at the moment...

</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica">Simply add 600 mL H2O to 100 mL of 70% HNO3 and then measure up 15g of the solution and use it for whatever you are doing. That is 10% HNO3.</font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">No, this won't work! 100mL of 70% HNO₃ is 142g, therefore containing 99.4g of HNO₃. The final solution will weigh 742g, with 99.4g of HNO₃, therefore it will be 13.4%!

Frogfot, that table would be a nice thing for what is currently the "Nitric Acid" section, please do scan it, host it somewhere and provide us a link. Or, you could scan it, e-mail the scan to me and I will host it and post a link.

I still think this is a potentially useful topic, so I'll just clean it up a bit and let it carry on.

See ya later gatecrasher, we'll miss you I'm sure :rolleyes: :p .

[Anthony]

The funny thing was, he had his question answered three times and then stomped off in a huff because no one would help him! :D

I don't like his kewl-hugging either, but some people insist that we're too harsh :rolleyes:

I'd close this thread, but frogfot has a decent question he needs answering.

[Mr Cool]

There, that's better. I just got rid of the posts that were (quite rightly <img border="0" title="" alt="[Wink]" src="wink.gif" /> ) ridiculing gatecrasher, so if anyone seems to be replying to a post which doesn't exist, that is why...
Incidentally, the Staff are being nice. But if the members take the mickey out of an idiot and he decides to leave, well, that's not our fault :) .
Hehe, obviously three answers were just not enough to satisfy his enormous brain, he wanted more!

[rikkitikkitavi]

is this the so called three-strike-law, and you are out ? :)

/rickard

[frogfot]

Heres HNO₃
<a href="http://www.geocities.com/frogfot/stuff/hno3.png" target="_blank">http://www.geocities.com/frogfot/stuff/hno3.png</a>
And here's it recognized, in .xls (had nothing to do :rolleyes: )
<a href="http://www.geocities.com/frogfot/stuff/hno3.xls" target="_blank">http://www.geocities.com/frogfot/stuff/hno3.xls</a>

Also specific gravity for H₂SO₄, tryed to recognize, but it sucked (somebody have spilled some crap on those two pages)
<a href="http://www.geocities.com/frogfot/stuff/h2so4.png" target="_blank">http://www.geocities.com/frogfot/stuff/h2so4.png</a>

Mr Cool, can you download them, maby change extension or resize.. i dont know if .png is optimal for such things.

[vulture]

The key to correctly calculating concentrations in liquids is the density. Try mixing ethanol and water and you'll see what I mean.

Once you know the density of your starting and you final concentration there should be nothing left to stop you.

[Arthis]

I was wondering if the density function of the concentration of HNO3 was a line, or a curv ? It would be easy, since d(H2O)=1...
Anyway the approximation should not be too big, and this method should work (for approximated ratios needed...); d(HNO3 pure)=1.51

[metafractal]

Hmm... now lets see:
Density : % HNO3 By Weight

1.0 : 0.3
1.1 : 17.6
1.2 : 32.9
1.3 : 48.4
1.4 : 67.0
1.5 : 96.7

At first it looks like a linear relationship ('line'), but it develops a slight exponential incline ('curv') in the higher Density/%HNO3s. Its neither really, there are multiple factors affecting it. One could probably get away with treating it as a linear function (line of best fit) for most practical purposes, but its probably best to look up the tables for any serious procedures :) .