Traveller
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explanation of chemical symbols
This is an excerpt from the book "Advances in Gold Ore Processing" by M.D. Adams:
"Laboratory-scale tests were conducted on 20% solids slurry containing 25 g/L NaOCl and 0.35 M HCl."
I understand the "g/L" to be grams per litre, of course, but what kind of measurement is "0.35 M"?
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gutter_ca
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"M" in this case indicates molarity, commonly used for acids and bases. In this case, there are 0.35 moles of HCl per liter of solution.
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bfesser
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This is a ridiculous thread. Please do some research on your own next time before posting. <em>Any</em> introductory chemistry material
will cover <a href="http://en.wikipedia.org/wiki/Concentration" target="_blank">concentration</a> <img src="../scipics/_wiki.png" />
and <a href="http://en.wikipedia.org/wiki/Molar_concentration" target="_blank">molarity</a> <img src="../scipics/_wiki.png" />.
Also, please post in the appropriate forum–this belongs in <strong><a
href="forumdisplay.php?fid=12">Beginnings</a></strong>.
<a href="http://lmgtfy.com/?q=What+does+%27M%27+stand+for+in+chemistry%3F&l=1" target="_blank">What does 'M' stand for in
chemistry?</a> <img src="../scipics/_ext.png" />
[Edited on 7/9/13 by bfesser]
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Traveller
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I see. So, if a person had 34% Muriatic acid, is there a way to convert 0.35 moles to g/L?
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bfesser
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<a href="http://en.wikipedia.org/wiki/Mole_(unit)" target="_blank">Moles</a> <img src="../scipics/_wiki.png" /> is not the same as
molarity. Again, the information you seek can easily be found by conducting a web search.
[Edited on 7/9/13 by bfesser]
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Traveller
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Excuse me but, everything I've found on the Web is so complicated, I am having trouble understanding what they are trying to say. This is why I asked
for an explanation here.
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Traveller
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moles?
The following is an excerpt from "Advances in Gold Ore Processing" by M.D. Adams:
"Laboratory-scale tests were conducted at room temperature on 20% solids slurry containing 25 g/L NaOCl and 0.35 M HCl."
I understand the g/L to be grams per litre but the "M" has me a bit confused. I'm told the "M" stands for moles. I looked up the whole mole/molar
thing on the Net and, although I understand it to be a mass per volume thing, the actual way of determining just how much HCl to add to a litre to
achieve 0.35 moles escapes me.
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bfesser
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Please don't <a href="viewthread.php?tid=23366">double/cross post</a>. But thanks for using the appropriate forum.
Perhaps you're one of those people who don't learn well by reading.
Try this video I found with a 2 second Google search but haven't watched:
<iframe sandbox width="420" height="315" src="http://www.youtube.com/embed/ryfLrSWxaGA" frameborder="0" allowfullscreen></iframe>
[Edited on 2/14/13 by bfesser]
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Vargouille
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There is, of course, a way to convert from molarity (moles per liter) to grams per liter. If you know the molar mass (given in grams per mole), you
can calculate it. Multiplying a molarity by a molar mass will cancel the units for moles and give you just g/L.
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Traveller
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If I could figure out how to delete the other thread, it would be gone by now.
I followed the search you posted a link to and, although I can grasp the concept of a mole being a measurement of a concentration of a substance in a
solution, I am still no closer to understanding how many ml. of HCl have to be added to a litre of solution to achieve 0.35 M.
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Traveller
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Oops, didn't see right away that you posted a video as well.
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DraconicAcid
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To convert the 34% "muriatic acid" to a molarity would require the density of the acid. Luckily for you, this can be looked up in the CRC handbook of
Chemistry and Physics, which tells me that 34% hydrochloric acid is 10.9 M. So you'd have to dilute it by a factor of 31. Measure out 32 mL of your
34% acid (careful!! That stuff is nasty!) and dilute it to 1.0 L.
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bfesser
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Sorry. I tend to edit my replies many times after posting... you probably read it before I had finished with it.
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cAMP
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By way of explanation
Can a mod please move this topic to Beginnings...
Anyway, molarity or M means "moles per liter" or m/L and is a convenient way of expressing concentration. Moles are a unit of measure, like a dozen
or a gross, meaning 12 and 144 respectively. A mole is 6.02x10^23 of something. This is an enormous number, but considering the smallness of atoms,
a mole of a substance is usually a measurable, easily defined amount. For example, one mole of sodium chloride measures 58.44 grams / mole.
Since molarity is a measure of concentration, a solution containing one mole of sodium chloride per liter of water would contain 1 liter of water (the
solvent) and one mole (6.02x10^23 molecules of sodium chloride, which have a mass of 58.44 grams). This would be 1M or 1 molar solution of sodium
chloride.
For your hydrochloric acid, it's a bit more complicated, because HCl(aq) is usually measured for non-scientific purposes as a weight percentage of HCl
gas disoolved in water, using a unit of measurement called Baumé units. But there are charts to look this up online. 34% HCl by weight converts to
10.90 molarity, which is calculated based on density and the weight percentage.
If you know that you have a 10.90 molar solution of HCl in water, you know that you have 10.90 moles per liter of HCl. Figure out the molar mass of
HCl and multiply by 10.90 and you will have your answer in g / L.
In the future, please try to do your homework first, and then ask these types of questions in the Beginnings section of the site.
"You just spent the entire night arguing grand unification theories with Albert Einstein!" - Geordi LaForge
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IrC
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Quote: Originally posted by DraconicAcid  | | To convert the 34% "muriatic acid" to a molarity would require the density of the acid. Luckily for you, this can be looked up in the CRC handbook of
Chemistry and Physics, which tells me that 34% hydrochloric acid is 10.9 M. So you'd have to dilute it by a factor of 31. Measure out 32 mL of your
34% acid (careful!! That stuff is nasty!) and dilute it to 1.0 L. |
As new to chemistry as this member sounds I think I would include also the warning "add the acid to water" "DO NOT ADD THE WATER TO ACID!".
"Science is the belief in the ignorance of the experts" Richard Feynman
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Traveller
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Okay, now it makes sense. Most of the things I was reading didn't go into the same detail as the guy in the video did.
I even managed to find a calculator online that will convert moles to grams (and vice versa), if you know the molar mass of the compound.
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Traveller
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Sorry about posting this in this forum. I re-posted it in Beginnings, as one member suggested, but couldn't figure out how to delete this thread from
this forum.
I know this is elementary stuff to you guys, but to me it was quite confusing. You fellows have done a much better job of explaining this than
anything on the Internet, except, of course, for the video bfesser found and posted for me on my Beginnings thread.
And thanks for looking out for me, IrC, with the warning to add acid to water and not the other way around. I already knew this, but it's good to see
someone looking out for the inexperienced.
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Polverone
Now celebrating 21 years of madness
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Threads Merged
17-2-2013 at 23:20 |
bfesser
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Thread Moved
9-7-2013 at 12:21 |
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