Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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my_2¢
 
Posts: n/a
Default ACID QUESTION

Please excuse this question; I realize this must seem elementary but I
am quite stymied and it entails a work related situation.

Cleaning out a acid cupboard where I work there are several bottles of
technical grade HNO3 which would be approx 70% but there are others
which are marked as "Fuming" (current date). My question is does there
exist a simple method to determine the percentage of acid if no
specific gravity info is present (i.e. 1.43, 1.50. etc, etc) ?

There are some other bottles that are student's from last semester
that have a variety of information dealing with temp...can HNO3 be
"cooked" to a higher percentage (exposed to heat, thus reducing the
water content? I was told that under no circumstances to get rid of
the higher percentage grades as they cost quite a bit more money. But
if they can be reduced, why pay for a higher percentage? I am quite
aware of the "kitchen" methodologies of extraction w/ methylene
chloride and destilation but I always wondered why a higher percentage
was simply not produced via evaporation?


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  #2   Report Post  
Harold & Susan Vordos
 
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Default ACID QUESTION


"my_2¢" wrote in message
...
Please excuse this question; I realize this must seem elementary but I
am quite stymied and it entails a work related situation.

Cleaning out a acid cupboard where I work there are several bottles of
technical grade HNO3 which would be approx 70% but there are others
which are marked as "Fuming" (current date). My question is does there
exist a simple method to determine the percentage of acid if no
specific gravity info is present (i.e. 1.43, 1.50. etc, etc) ?

There are some other bottles that are student's from last semester
that have a variety of information dealing with temp...can HNO3 be
"cooked" to a higher percentage (exposed to heat, thus reducing the
water content? I was told that under no circumstances to get rid of
the higher percentage grades as they cost quite a bit more money. But
if they can be reduced, why pay for a higher percentage? I am quite
aware of the "kitchen" methodologies of extraction w/ methylene
chloride and destilation but I always wondered why a higher percentage
was simply not produced via evaporation?



I'm no chemist, but my work with precious metals got me somewhat acquainted
with acids. One of the things you get when you buy the higher
concentrations isn't just that, you also pay for the level of purity.
Reagent grade nitric acid was guaranteed to have fewer contaminants, for
which you paid more money. A lot more money. I'm sure that, depending on
the methods employed to manufacture the acids, high levels of quality were
also obtained by tech grades, but there was no guarantee. I can only
assume that it would be much like buying bar stock for the shop. If you
want a guarantee of quality, you buy certified material, for which you pay
slightly more, if not a lot more.

Perhaps someone in the chemical industry will clarify this for all of us.

Harold


  #3   Report Post  
Don Wilkins
 
Posts: n/a
Default ACID QUESTION

On Sun, 09 Nov 2003 18:00:08 -0700, my_2¢
wrote:

,;Please excuse this question; I realize this must seem elementary but I
,;am quite stymied and it entails a work related situation.
,;
,;Cleaning out a acid cupboard where I work there are several bottles of
,;technical grade HNO3 which would be approx 70% but there are others
,;which are marked as "Fuming" (current date). My question is does there
,;exist a simple method to determine the percentage of acid if no
,;specific gravity info is present (i.e. 1.43, 1.50. etc, etc) ?


No.

White fuming nitric acid contains more than 97.5% , less than 2%
water, and less than 0.5% of oxides of nitrogen. It should be
colorless or pale yellow. It is decomposed by sunlight or elevated
temperatures which should suggest why you can't make it by boiling off
water.

Red fuming nitric acid contains more than 86% nitric acid, 6-15%
oxides of nitrogen, and less than 5% water.

Open bottles of chemicals are usually of unknown composition and not
worth saving. Be careful with this stuff as it has a fast and vicious
bite.

,;
,;There are some other bottles that are student's from last semester
,;that have a variety of information dealing with temp...can HNO3 be
,;"cooked" to a higher percentage (exposed to heat, thus reducing the
,;water content? I was told that under no circumstances to get rid of
,;the higher percentage grades as they cost quite a bit more money. But
,;if they can be reduced, why pay for a higher percentage? I am quite
,;aware of the "kitchen" methodologies of extraction w/ methylene
,;chloride and destilation but I always wondered why a higher percentage
,;was simply not produced via evaporation?
,;
,;
,;-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
,;http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
,;-----== Over 100,000 Newsgroups - 19 Different Servers! =-----


  #4   Report Post  
Engineman1
 
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Default ACID QUESTION

In article , my_2¢
writes:

.can HNO3 be
"cooked" to a higher percentage (exposed to heat, thus reducing the
water content? I was told that under no circumstances to get rid of
the higher percentage grades as they cost quite a bit more money. But
if they can be reduced, why pay for a higher percentage? I am quite
aware of the "kitchen" methodologies of extraction w/ methylene
chloride and destilation but I always wondered why a higher percentage
was simply not produced via evaporation?


Doing a Google search for fuming nitric acid on
http://www.ch.ic.ac.uk/rzepa/mim/env...itric_text.htm
I got:

100% pure, anhydrous nitric acid is a colourless anhydrous solid. What we call
'concentrated nitric acid' is actually a solution of 68% by weight HNO3 in
water (16M), and is often pale yellow as a result of photochemical
decomposition which gives NO2. By dissolving even more NO2 into the pure
material produces red 'fuming' nitric acid, which is an extremely powerful acid
and oxidising agent using in the semiconductor industry for cleaning silicon
wafers.
  #5   Report Post  
Paul K. Dickman
 
Posts: n/a
Default ACID QUESTION


my_2¢ wrote in message ...
Please excuse this question; I realize this must seem elementary but I
am quite stymied and it entails a work related situation.

Cleaning out a acid cupboard where I work there are several bottles of
technical grade HNO3 which would be approx 70% but there are others
which are marked as "Fuming" (current date). My question is does there
exist a simple method to determine the percentage of acid if no
specific gravity info is present (i.e. 1.43, 1.50. etc, etc) ?




Titration will give you the percentage, but specific gravity is the easy
way.

Paul K. Dickman







  #6   Report Post  
JMartin957
 
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Default ACID QUESTION

Measuring the specific gravity with a hydrometer might get you close.
Titrating - neutralizing a specific amount of the unknown strength acid against
a known concentration of a base, using an indicator such as phenolpthalein
solution to determine when you hit neutral, measuring the exact amount of base
needed and then doing the calculations - will give you an exact number.

Many solutions have what is called an azeotropic point, or constant boiling
mixture. When you boil them, either the acid or the water will come off faster
until that point is reached. I couldn't find it in my chemical handbook (it
should be there) and can't remember where it is for nitric acid, but believe it
is well below the fuming or the 70 percent levels.

Hope this helps.

John Martin
  #7   Report Post  
Bert
 
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Default ACID QUESTION

"Harold & Susan Vordos" wrote:

I'm no chemist, but my work with precious metals got me somewhat acquainted
with acids. One of the things you get when you buy the higher
concentrations isn't just that, you also pay for the level of purity.


Not true. Purity and concentration are independent variables. Both lab
grades and technical grades are available in a variety of
concentrations. Lab grades cost more than technical grades; higher
concentrations cost more than lower concentrations; and smaller
quantities cost more (on a $/volume basis) than larger quantities,
sometimes much more.

For example, VWR offers 0.5 L of reagent grade HNO3 for $49.35 (70%)
and $184.55 (90%). The 70% is also offered in a 2.5 L container for
$67.65, which is less than $20 more than the cost of the 0.5 L
container, or nearly a 73% discount! Go figure. VWR doesn't list any
technical grade HNO3.

Finding a source for small quantities of technical grade HNO3,
especially in the higher concentrations, can be problematic. If you
know of a good source, please share!

Bert
  #8   Report Post  
Harold & Susan Vordos
 
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Default ACID QUESTION


"Bert" wrote in message
...
"Harold & Susan Vordos" wrote:

I'm no chemist, but my work with precious metals got me somewhat

acquainted
with acids. One of the things you get when you buy the higher
concentrations isn't just that, you also pay for the level of purity.


Not true. Purity and concentration are independent variables. Both lab
grades and technical grades are available in a variety of
concentrations. Lab grades cost more than technical grades; higher
concentrations cost more than lower concentrations; and smaller
quantities cost more (on a $/volume basis) than larger quantities,
sometimes much more.

For example, VWR offers 0.5 L of reagent grade HNO3 for $49.35 (70%)
and $184.55 (90%). The 70% is also offered in a 2.5 L container for
$67.65, which is less than $20 more than the cost of the 0.5 L
container, or nearly a 73% discount! Go figure. VWR doesn't list any
technical grade HNO3.

Finding a source for small quantities of technical grade HNO3,
especially in the higher concentrations, can be problematic. If you
know of a good source, please share!

Bert


Sorry to say my information reflects my experiences of days long gone. I
sold my refining business in '94, in no small part because of the terrible
increases in the price of acids and more restrictions placed on me because
of my location, which was not exactly suited to the activities at hand.
However, I was buying tech grade HNO3 from Great Western Chemical for just
over $200 per drum, which I owned, a lucky purchase from the UofU surplus
store. As you know, the drums are stainless and have a tremendously
expensive deposit ($400 at that time) if you don't happen to own your own.
I went through a drum (50 gallons as I recall) about twice a year.

The only purchases of reagent grade nitric I made were in 5 pint bottle case
lots, and they were higher in concentration, and correspondingly higher in
price, too. It was for that reason I assumed that quality went hand in
hand with concentration, but I realize that there could be a need for high
purity at lower concentrations, so what you had to say makes sense. I
used reagent grade for my testing solutions, so my demand was relatively
small.

You think HNO3 is expensive? Try pricing bromine! I used that as an
oxidizer for gold recovery from complex ores using cyanide. Killer
expensive in small quantities, yet completely affordable if bought in
volume. At least it was that way back then (about 1980).

Oh, yeah. While I could have stayed in business, I chose to retire early.
Operating costs didn't really drive me away. Love being retired!

Harold


  #9   Report Post  
Don Wilkins
 
Posts: n/a
Default ACID QUESTION

On Sun, 09 Nov 2003 18:00:08 -0700, my_2¢
wrote:

,;Please excuse this question; I realize this must seem elementary but I
,;am quite stymied and it entails a work related situation.
,;
,;Cleaning out a acid cupboard where I work there are several bottles of
,;technical grade HNO3 which would be approx 70% but there are others
,;which are marked as "Fuming" (current date). My question is does there
,;exist a simple method to determine the percentage of acid if no
,;specific gravity info is present (i.e. 1.43, 1.50. etc, etc) ?


From the American Chemical Society Specifications Reagent Chemicals
Eighth Edition

Assay....69.0-71.0% HNO3

Assay (By acid-base titrimetry) Tare a small glass-stoppered flask
containing about 15 mL of water. Quickly pipet about 2 mL of the
sample under the water surface, stopper, cool, and weigh accurately.
dilute with about 40 mL of water, add 0.15 mL of methyl orange
indicator solution and titrate with 1 N sodium hydroxide. One
milliliter of 1 N sodium hydroxide corresponds to 0.06301 g of HNO3.

I can verify that it is a good procedure as I was a member of the ACS
Committee for Analytical Reagent Chemicals that wrote the book.
Whether or not it is simple depends on your skills and access to some
elementary lab equipment.

My advice is dilute it and get rid of it.
,;
,;There are some other bottles that are student's from last semester
,;that have a variety of information dealing with temp...can HNO3 be
,;"cooked" to a higher percentage (exposed to heat, thus reducing the
,;water content? I was told that under no circumstances to get rid of
,;the higher percentage grades as they cost quite a bit more money. But
,;if they can be reduced, why pay for a higher percentage? I am quite
,;aware of the "kitchen" methodologies of extraction w/ methylene
,;chloride and destilation but I always wondered why a higher percentage
,;was simply not produced via evaporation?
,;
,;
,;-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
,;http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
,;-----== Over 100,000 Newsgroups - 19 Different Servers! =-----


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my_2¢
 
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Default ACID QUESTION (thank you!)

I was surprised at the amount of information as response to my query,
I certainly appreciate it.

It appears that there is no easy and simple way to render a higher
percentage grade and thus the extreme price differentiation. Vacuum
Distillation seems like a good way to have a "problem".


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