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Posted by Mark Rand on January 27, 2008, 5:05 am
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On Sun, 27 Jan 2008 04:38:12 +0000, Christopher Tidy
>>
>>
>> You can buy nitric acid from lpchemicals, but they have a minimum £50
>> order (plus carriage and VAT).
>
>I checked their website, but can only find dilute nitric acid. It's my
>understanding that you need concentrated nitric acid.
>
It's in the section marked Acids/Alkalines (Nitric Acid LR) :-)
I know this because I have a litre bottle that I bought from them.
You want about 10% acid in industrial spirit for etching ferrous materials.
For some website-related reason, you won't see industrial spirit in the list
of solvents, but if you search for "industrial" you'll find it.
Mark Rand
RTFM
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Posted by Mark Rand on January 27, 2008, 5:08 am
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>
>You want about 10% acid in industrial spirit for etching ferrous materials.
>
Finger trouble... 1% for lapped/ground sections. 10% is for macro etching
samples and blowing up the workshop...
Mark Rand
RTFM
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Posted by Christopher Tidy on January 29, 2008, 2:48 am
Please log in for more thread options Mark Rand wrote:
> On Sun, 27 Jan 2008 04:38:12 +0000, Christopher Tidy
>
>
>
>>>
>>>You can buy nitric acid from lpchemicals, but they have a minimum £50
>>>order (plus carriage and VAT).
>>
>>I checked their website, but can only find dilute nitric acid. It's my
>>understanding that you need concentrated nitric acid.
>>
>
>
> It's in the section marked Acids/Alkalines (Nitric Acid LR) :-)
Thanks. That would explain why they don't list the concentration. For
some reason I assumed that "Laboratory Reagent" was pre-diluted stuff
for giving to students.
Pity about the £50 minimum order charge. That's more that I want to
spend. They don't state their carriage charge either. It's seems they're
in Cheshire, so maybe I could pick up a bottle from them? That's if they
aren't going to be unnecessarily fussy.
My dad said he bought a bottle of concentrated nitric acid from his
village chemist when he was a boy.
Best wishes,
Chris
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Posted by Peter Fairbrother on January 29, 2008, 3:58 am
Please log in for more thread options Christopher Tidy wrote:
> Mark Rand wrote:
>> On Sun, 27 Jan 2008 04:38:12 +0000, Christopher Tidy
>>
>>
>>
>>>>
>>>> You can buy nitric acid from lpchemicals, but they have a minimum
>>>> £50 order (plus carriage and VAT).
>>>
>>> I checked their website, but can only find dilute nitric acid. It's
>>> my understanding that you need concentrated nitric acid.
>>>
>>
>>
>> It's in the section marked Acids/Alkalines (Nitric Acid LR) :-)
>
> Thanks. That would explain why they don't list the concentration. For
> some reason I assumed that "Laboratory Reagent" was pre-diluted stuff
> for giving to students.
It's fairly pure nitric acid of about 70% concentration, ie with 30%
water and only a little bit of other substances. It's the right stuff to
make nital with.
Chemicals usually come in 3 main grades, Technical, LR and AR. There are
other grades though, eg food, ultra-pure, semiconductor and
spectroscopic grades.
Technical grade is approximately "mostly the right stuff", and usually
will be about 95% pure, though this will depend on the chemical involved.
LR or "laboratory reagent" is a grade of purity, sort of. Usually LR
stuff will be 98-99% pure or so. Really however, LR is saying it is
suitable for use as a general laboratory reagent.
AR, or "analytical reagent" is usually even purer, maybe 99.9%. Again it
varies, and AR is just saying that it's suitable for analytical work.
These can vary a bit, especially AR, when the label may say that there
is only a tiny bit of some otherwise common impurity, which would mess
up the use of the chemical in (some) analytical situations; but there
may be a fair bit of another impurity which doesn't affect the
analytical use of the chemical. AR labels usually give lists of maximum
levels of impurities, and an assay.
A few chemicals are slightly different, for instance nitric and
hydrochloric acids, ammonia solutions etc. They still come in grades,
but it assumed that they contain water, which is not counted as an
impurity or a diluent - for nitric acid, it's usually about 70% acid,
for hydrochloric acid it's about 35% acid, and so on.
The reasons for these differences vary, for nitric acid it's because it
fumes and is dangerous to store at concentrations about 70%, for
hydrochloric acid it's because only 35% of HCl will dissolve in water
(HCl is a gas), and so on.
However, "nitric acid", unless it has something else tacked on, is
usually assumed to be 70% in concentration when you buy the chemical. It
also comes in grades as above, technical, LR and AR, but these refer to
the levels of impurities in the acid, not the concentration of acid,
which will always be 70% or so.
Now that's more than you wanted to know, isn't it :)
>
> Pity about the £50 minimum order charge. That's more that I want to
> spend. They don't state their carriage charge either. It's seems they're
> in Cheshire, so maybe I could pick up a bottle from them? That's if they
> aren't going to be unnecessarily fussy.
You could 'phone and ask.
-- Peter Fairbrother
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Posted by Christopher Tidy on February 2, 2008, 4:06 pm
Please log in for more thread options Peter Fairbrother wrote:
<snip>
> You could 'phone and ask.
I did. Looks like the cheapest thing for me to do is to collect a single
bottle from their premises in Cheshire. They said I can do this with no
minimum order charge.
Best wishes,
Chris
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>>
>> You can buy nitric acid from lpchemicals, but they have a minimum £50
>> order (plus carriage and VAT).