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tom haggen
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Density
is density always measured in the units of grams/cubic centimeters (g/cm3)? because on this website www.roguesci.org/megalomania/synthesis3.html#nitric it doesn't specify the units. also if all i have is a measuring container that measures
liquid in milliliters and I need to know how much that is in cubic centimeters could someone remind me of the simple conversion between these 2 units
of measurement, sorry about the elementry math questions but better safe than sorry
-tom
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Blind Angel
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1 ml = 1cm<sup>3</sup>
[Edited on 30-11-2003 by Blind Angel]
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tom haggen
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thx
that what my hypothesis was thanks for clearing that up. as for the website I read farther and found water, and saw the density for that was 1 so i
know what units hes using now.
P.S. im starting to like the metric system a little more now
-tom
[Edited on 30-11-2003 by tom haggen]
[Edited on 30-11-2003 by tom haggen]
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axehandle
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The metric system is superior in every way.
For example, if I say that my penis is 18cm long, it sounds better than 7 inches.... =)
Edit: I'm drunk now.
[Edited on 2004-2-14 by axehandle]
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hodges
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Isn't density measured relative to water? I don't think the units (metric or other) matter.
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thunderfvck
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Yeah, denstiy is measured relative to water. We say that 1 gram of water is 1 ml. I guess it doesn't matter about the units because the geenral
idea is derived with respect to water, but metric is so much easier!
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Hermes_Trismegistus
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| Quote: | Originally posted by Blind Angel
1 ml = 1cm<sup>3</sup>
[Edited on 30-11-2003 by Blind Angel] |
Yes, But only of pure water at standard temperature and pressure!
and if something has a quoted density of say 1.816 it refers to 1.816 grams per cubic centimeter (at standard temperature and pressure).
(just wanted to make one final clarifying statement.)
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vulture
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For water it's not at the standard temperature; it's the density measured at 4C or 277,15K.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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Magpie
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density vs specific gravity
Density is in absolute units, e.g. g/ml, g/cm3, etc. Density of water at room temperature would be slightly less than 1 g/cm3.
Specific gravity is a number without units that is referenced to some standard material at some standard condition, normally H2O at 1 atm and 4 deg C.
Specific gravity of mercury at room temperature would be about 13, IIRC.
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Hermes_Trismegistus
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| Quote: | Originally posted by vulture
For water it's not at the standard temperature; it's the density measured at 4C or 277,15K. |
Is that because, it is at that temperature that liquid water is at its most dense?
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jimwig
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there is a neat device for measuring the density of solids.
its a container with a spill way on it to catch all the liquid displaced from placing a solid in the liquid.
weigh the solid
weigh the water it displaces
ration equals density ratio
gold = 19 something
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t_Pyro
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| Quote: | Originally posted by jimwig
there is a neat device for measuring the density of solids. |
It's called a "eureka can", after Archimede's exclamation.
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unionised
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The SI unit of density is the Kg/m^3 Beware of this when looking at data from physics books (They think the density of water is about a thousand).
Strictly the density of water isn't 1 g/ cm^3 but it is 1 g/ ml. The difference is about 27 parts in a million and I don't see that
mattering much. (It's because they couldn't make the prototype kilogram agree with the prototype metre to better than that accuracy).
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jimwig
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are not a ml and cc^3 the same amount?
[Edited on 3-3-2004 by jimwig]
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t_Pyro
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There's no such thing as cc^3. If what you mean is 1<b>cm<sup>3</sup></b> or cc (cubic centimetre), the answer is yes.
1m is defined as the path traveled by light in vacuum in 1/299,792,458 of a second.
1Kg is equal to the mass of the international prototype of the kilogram, a certain platinum-iridium cylinder.
For more details, see <a href="http://physics.nist.gov/cuu/Units/current.html">this</a>.
[Edited on 8-3-2004 by t_Pyro]
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I am a fish
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| Quote: | Originally posted by t_Pyro
There's no such thing as cc^3. |
#include <pedantry.h>
There is in 9-dimensional or higher space.
1f `/0u (4|\\| |234d 7|-|15, `/0u |234||`/ |\\|33d 70 937 0u7 /\\/\\0|23.
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t_Pyro
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PEDANTRY
n : a ostentatious and inappropriate display of learning
From dictionary.com.
Forgive me, because I'm still one of the lesser mortals limited to a paltry 3 dimensions. You're absolutely right, though.
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tom haggen
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So if I have some 35% NaOH that weighs somewhere around 1.41g/cm3. does that mean that it is 35% NaOH by weight or does it mean that it is 35% NaOH by
volume. I used a density chart to calculate concentration.
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t_Pyro
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35% NaOH could be w/w (weight per weight) , or w/v (weight per volume) .
If it's w/v, that means there is 35 gms of pure NaOH per 100 ml of the solution. That amounts to a molarity of 35/40*10= 8.75 M
If it's w/w, that means that there is 35 gm of pure NaOH per 100 gm of the solution. If the density is 1.41g/cm<sup>3</sup>, that
amounts to a molarity of (35/40)/(100/1.41)*1000 = 12.3375 M. Note the difference in the two values.
If the concentration was written on a laboratory reagent bottle, it most probably refers to w/w composition. If that's the case, the relative
density will also be printed on the label.
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Magpie
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concentration expressed in %
Tom, I'd say that if you have what is normally a solid dissolved in a liquid then it will be wt%. However, if you have a liquid dissolved in a
liquid then it will likely be vol%, like alcohol in water for alcoholic beverages or food flavorings.
Chemists are pretty good about giving you the basis, but consumer products are notoriously poor.
Gas in gas is normally vol%, which is also mole %.
[Edited on 13-3-2004 by Magpie]
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tom haggen
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well i think i'm going with weight because after all I weighed 100ml of this solution and it weighed 141grams. So i determined that it was like
35% sodium hydroxide. Thats were it fell on the density chart if I remember correctly. so if I have 141grams of 35% NaOH than I have 49grams of pure
NaOH.
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axehandle
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I'm so very grateful that I've grown up using the SI metric system... 
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Magpie
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amen
Somewhat off topic, but yes, what a pain it is to have to be able to work between 2 or more systems of units. As a chemical engineering student and
as a practicing engineer I have had to be able to convert constantly between metric and English. What a colossal waste of time. The US government
periodically issues mandates about going metric but the English system is so entrenched that it is going slowly. I have to keep 2 complete wrench
sets to be able to keep stuff repaired around the house, cars, etc.
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axehandle
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Like someone once said: "You approach the metric system inch by inch".
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12AX7
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| Quote: | Originally posted by Magpie
I have had to be able to convert constantly between metric and English. |
Fuck the French and their system. 
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