Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?

cheers,
Mike

On 19/06/2020 14:08, Mike McLeod wrote:
Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?


AIUI, acid concentration and "strength" are different things

https://sciencing.com/difference-between-strength-concentration-8601963.html

On 19/06/2020 14:13, Pancho wrote:
On 19/06/2020 14:08, Mike McLeod wrote:
Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?


AIUI, acid concentration and "strength" are different things

https://sciencing.com/difference-between-strength-concentration-8601963.html



I meant to add, back when I did A'level we measured concentration by
titration.

Mike McLeod Wrote in message:
Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?

cheers,
Mike


How many corpses are you trying to dissolve?
--
Jimk


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

On Fri, 19 Jun 2020 14:08:40 +0100, Mike McLeod wrote:

Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?

cheers,
Mike

ISTR it's to do with equilibrium: sulphuric is v. concentrated before the
fumes (sulphur trioxide?) coming off balance the SO3 dissolving; Nitric
fumes rather more; HCl fumes a lot, even when not fully concentrated.
They are all strong acids, even at v. low concentrations but are quite easy
to rinse out. Organic acids (citric, acetic etc.) are weak acids, do not
fully dissociate in solution and retain the same concentration of ions until
a certain dilution is reached, i.e. buffered, so can be harder to rinse
away.
As an aside, pieces of fruit stuck between teeth will, apart from providing
sugar(s) for bacteria, also remain acid for quite a while in spite of
dilution by saliva and reaction with enamel.
--
Peter.
The gods will stay away
whilst religions hold sway

On Fri, 19 Jun 2020 14:08:40 +0100, Mike McLeod
wrote:

Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?

You can tell the strength of an acid by the strength of the conjugate
base it forms. Strong acids form weak conjugate bases and vice versa.
It's all to do with protons and how likely they are to cleave and stay
cleaved. That won't help you one iota, though, I just thought I'd
mention it to show off.

On 19/06/2020 14:08, Mike McLeod wrote:
Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?

That's the way you do it for car battery acid. You can get special
hydrometers with a rubber bulb to suck the acid from the cells.

I don't know how you would convert the specific gravity to
concentration. Ask a chemist.

--
Max Demian

Mike McLeod wrote:
Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?

cheers,
Mike

Just take the concentration on the bottle as
accurate, do the maths for dilution by volume,
to get it to where you want.

"Why is acid always added to water, and not the reverse"

https://antoine.frostburg.edu/chem/s...add-acid.shtml

You won't have the glassware to do a titration
(volumetric flasks, gram scale, burette, phenolphthalein,
beakers).

Preps to a certain concentration, are based on manufacturing
practice or practical limits. We don't make substances that
explode spontaneously at high concentrations, on purpose that way.
We make things with known and stable characteristics.

Of the "strong" materials you might run into, I might want
to "assay" ammonia in a bottle. I had a bottle of that
which I used to dilute and make window cleaner (without
any "polish" in it), and one day I opened that bottle,
and only water was in there. The ammonia had "vanished" :-)

Since ammonia is a watched substance, the bottle I had, I
can't buy another. That's the ****er of the thing.

Paul

On 19/06/2020 19:15, Tim Streater wrote:
On 19 Jun 2020 at 19:09:42 BST, Paul wrote:

Mike McLeod wrote:
Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?

cheers,
Mike

Just take the concentration on the bottle as
accurate, do the maths for dilution by volume,
to get it to where you want.

"Why is acid always added to water, and not the reverse"

I thought that was only the case for sulphuric?

I used to swallow the blotting paper as it came


--
Climate Change: Socialism wearing a lab coat.

On 19/06/2020 18:24, Max Demian wrote:
On 19/06/2020 14:08, Mike McLeod wrote:
Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?

That's the way you do it for car battery acid. You can get special
hydrometers with a rubber bulb to suck the acid from the cells.

I don't know how you would convert the specific gravity to
concentration. Ask a chemist.

Oh please

https://www.engineeringtoolbox.com/i...ty-d_2163.html

Tim Streater wrote:
On 19 Jun 2020 at 19:09:42 BST, Paul wrote:

Mike McLeod wrote:
Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?

cheers,
Mike
Just take the concentration on the bottle as
accurate, do the maths for dilution by volume,
to get it to where you want.

"Why is acid always added to water, and not the reverse"

I thought that was only the case for sulphuric?


If there's a noteworthy exothermy, you'd probably
follow the rule.

You've probably noticed how warm the water gets
when you mix up Drano.

In a chem lab, I've only seen one loon manage to coat
the lab ceiling (and these are tall ceilings too) with
chemicals cooking in a refluxing setup. The number of
"oopsy" incidents was remarkably low. So not too many
"liquid headed for orbit" events in the lab. I'm sure
lots of people didn't follow the rules on acid order.

Sulphuric acid is a bitch. All my jeans in lab had
holes in 'em, thanks to sulphuric. You cannot neutralize
it fast enough, so don't bother... Sulphuric can react
with cotton in under a second, to its ruination.

If you're pipetting acid, *always* use a rubber bulb
to operate the pipette. No cowboy stuff.

Paul

On 19/06/20 14:37, PeterC wrote:
On Fri, 19 Jun 2020 14:08:40 +0100, Mike McLeod wrote:

Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?

cheers,
Mike

ISTR it's to do with equilibrium: sulphuric is v. concentrated before the
fumes (sulphur trioxide?) coming off balance the SO3 dissolving; Nitric
fumes rather more; HCl fumes a lot, even when not fully concentrated.

That's more-or-less correct. It's to do with the maximum stable amount
of their oxide reacting with water. For sulphuric acid, it's about 98%
sulphur trioxide content; for nitric acid about 73% nitrogen dioxide
content. Both can "dissolve" further amounts of their oxides, but they
are not stable, and form fuming sulphuric and fuming nitric acid.
Hydrochloric acid is simply a solution of hydrogen chloride in water -
it does not react with the water in the same way that the oxides do.

They are all strong acids, even at v. low concentrations but are quite easy
to rinse out. Organic acids (citric, acetic etc.) are weak acids, do not
fully dissociate in solution and retain the same concentration of ions until
a certain dilution is reached, i.e. buffered, so can be harder to rinse
away.

If you want a really strong acid, have a look he
https://en.wikipedia.org/wiki/Fluoroantimonic_acid

--

Jeff

On Fri, 19 Jun 2020 14:09:42 -0400, Paul
wrote:

Since ammonia is a watched substance, the bottle I had, I
can't buy another. That's the ****er of the thing.

I'm guessing this list of "watched substances" grows longer every
year. Is there an up-to-date list on the net anywhere?
Brick cleaner is strong hydrochloric acid. Diluted down, it makes a
very effective and dirt-cheap limescale remover; no scrubbing, just
dissolves it on contact forming a salt which is readily soluble -
being polar - in water and easily washed away.
Most of the fancy brand-name cleaning products you find in the
supermarkets are just heavily-diluted industrial chemicals you can buy
far cheaper and make much more effective if you know a bit of basic
chemistry and aren't afraid of builders merchants.

On Fri, 19 Jun 2020 22:01:06 +0100, Jeff Layman
wrote:

That's more-or-less correct. It's to do with the maximum stable amount
of their oxide reacting with water. For sulphuric acid, it's about 98%
sulphur trioxide content; for nitric acid about 73% nitrogen dioxide
content. Both can "dissolve" further amounts of their oxides, but they
are not stable, and form fuming sulphuric and fuming nitric acid.
Hydrochloric acid is simply a solution of hydrogen chloride in water -
it does not react with the water in the same way that the oxides do.

ISTR that the problem with hydrochloric is it forms an azeotropic
mixture at a relatively low concentration which makes further
purification very difficult. I don't think that occurs with the other
common mineral acids.

On Sat, 20 Jun 2020 01:08:17 +0100
Cursitor Doom wrote:

On Fri, 19 Jun 2020 22:01:06 +0100, Jeff Layman
wrote:

That's more-or-less correct. It's to do with the maximum stable
amount of their oxide reacting with water. For sulphuric acid, it's
about 98% sulphur trioxide content; for nitric acid about 73%
nitrogen dioxide content. Both can "dissolve" further amounts of
their oxides, but they are not stable, and form fuming sulphuric and
fuming nitric acid. Hydrochloric acid is simply a solution of
hydrogen chloride in water - it does not react with the water in the
same way that the oxides do.

ISTR that the problem with hydrochloric is it forms an azeotropic
mixture at a relatively low concentration which makes further
purification very difficult. I don't think that occurs with the other
common mineral acids.

I once worked at an aircraft wing treatment plant, and one of the tanks
contained a mixture of hydroflouric, nitric and chromic acids. Heated
to 140 deg. F. The sump under the circulating pumps contained a sludge
which indicated on the pH test paper at less than 0 pH.

--
Davey.

Davey wrote:
On Sat, 20 Jun 2020 01:08:17 +0100
Cursitor Doom wrote:

On Fri, 19 Jun 2020 22:01:06 +0100, Jeff Layman
wrote:

That's more-or-less correct. It's to do with the maximum stable
amount of their oxide reacting with water. For sulphuric acid, it's
about 98% sulphur trioxide content; for nitric acid about 73%
nitrogen dioxide content. Both can "dissolve" further amounts of
their oxides, but they are not stable, and form fuming sulphuric and
fuming nitric acid. Hydrochloric acid is simply a solution of
hydrogen chloride in water - it does not react with the water in the
same way that the oxides do.
ISTR that the problem with hydrochloric is it forms an azeotropic
mixture at a relatively low concentration which makes further
purification very difficult. I don't think that occurs with the other
common mineral acids.

I once worked at an aircraft wing treatment plant, and one of the tanks
contained a mixture of hydroflouric, nitric and chromic acids. Heated
to 140 deg. F. The sump under the circulating pumps contained a sludge
which indicated on the pH test paper at less than 0 pH.


What was the tank made out of ?

Paul

On 19/06/2020 22:14, Cursitor Doom wrote:
On Fri, 19 Jun 2020 14:09:42 -0400, Paul
wrote:

Since ammonia is a watched substance, the bottle I had, I
can't buy another. That's the ****er of the thing.

I'm guessing this list of "watched substances" grows longer every
year. Is there an up-to-date list on the net anywhere?
Brick cleaner is strong hydrochloric acid. Diluted down, it makes a
very effective and dirt-cheap limescale remover; no scrubbing, just
dissolves it on contact forming a salt which is readily soluble -
being polar - in water and easily washed away.

it also discolours chrome very badly. You have been warned.


Most of the fancy brand-name cleaning products you find in the
supermarkets are just heavily-diluted industrial chemicals you can buy
far cheaper and make much more effective if you know a bit of basic
chemistry and aren't afraid of builders merchants.



--
Karl Marx said religion is the opium of the people.
But Marxism is the crack cocaine.

On 20/06/20 01:21, Davey wrote:
On Sat, 20 Jun 2020 01:08:17 +0100
Cursitor Doom wrote:

On Fri, 19 Jun 2020 22:01:06 +0100, Jeff Layman
wrote:

That's more-or-less correct. It's to do with the maximum stable
amount of their oxide reacting with water. For sulphuric acid, it's
about 98% sulphur trioxide content; for nitric acid about 73%
nitrogen dioxide content. Both can "dissolve" further amounts of
their oxides, but they are not stable, and form fuming sulphuric and
fuming nitric acid. Hydrochloric acid is simply a solution of
hydrogen chloride in water - it does not react with the water in the
same way that the oxides do.

ISTR that the problem with hydrochloric is it forms an azeotropic
mixture at a relatively low concentration which makes further
purification very difficult. I don't think that occurs with the other
common mineral acids.

I once worked at an aircraft wing treatment plant, and one of the tanks
contained a mixture of hydroflouric, nitric and chromic acids. Heated
to 140 deg. F. The sump under the circulating pumps contained a sludge
which indicated on the pH test paper at less than 0 pH.

I'm surprised you had time to read the pH before the test paper
dissolved! What was that acid mixture needed for?

--

Jeff

On Sat, 20 Jun 2020 01:21:10 +0100, Davey wrote:

On Sat, 20 Jun 2020 01:08:17 +0100
Cursitor Doom wrote:

On Fri, 19 Jun 2020 22:01:06 +0100, Jeff Layman
wrote:

That's more-or-less correct. It's to do with the maximum stable
amount of their oxide reacting with water. For sulphuric acid, it's
about 98% sulphur trioxide content; for nitric acid about 73%
nitrogen dioxide content. Both can "dissolve" further amounts of
their oxides, but they are not stable, and form fuming sulphuric and
fuming nitric acid. Hydrochloric acid is simply a solution of
hydrogen chloride in water - it does not react with the water in the
same way that the oxides do.

ISTR that the problem with hydrochloric is it forms an azeotropic
mixture at a relatively low concentration which makes further
purification very difficult. I don't think that occurs with the other
common mineral acids.

I once worked at an aircraft wing treatment plant, and one of the tanks
contained a mixture of hydroflouric, nitric and chromic acids. Heated
to 140 deg. F. The sump under the circulating pumps contained a sludge
which indicated on the pH test paper at less than 0 pH.

HF is /very/ nasty! On the skin it continues to act even after rinsing and
needs injections to stop it.
We used it at work for a process in memories (as far as my memory goes after
40+ years!) and someone dropped a nearly full 2.5 li bottle (HDPE) with the
top off. Took a long time to clear up and needed full PPE. I suggested using
500 ml bottles; we did, until the cost was questioned and then bean-counters
won.
--
Peter.
The gods will stay away
whilst religions hold sway

On 19/06/20 22:14, Cursitor Doom wrote:
On Fri, 19 Jun 2020 14:09:42 -0400, Paul
wrote:

Since ammonia is a watched substance, the bottle I had, I
can't buy another. That's the ****er of the thing.

I'm guessing this list of "watched substances" grows longer every
year. Is there an up-to-date list on the net anywhere?
Brick cleaner is strong hydrochloric acid. Diluted down, it makes a
very effective and dirt-cheap limescale remover; no scrubbing, just
dissolves it on contact forming a salt which is readily soluble -
being polar - in water and easily washed away.

If you have some food-based things (saucepans, etc) you want descaled
use a spoonful of food-grade citric acid in a small amount of boiling
water. You get calcium citrate, which is quite soluble. Citric acid is
strong enough to be quite effective at scale removal, but not too strong
as to attack metal.

Most of the fancy brand-name cleaning products you find in the
supermarkets are just heavily-diluted industrial chemicals you can buy
far cheaper and make much more effective if you know a bit of basic
chemistry and aren't afraid of builders merchants.

True. Note that food-grade citric acid is available online and lasts a
long time.

--

Jeff

On 20/06/2020 01:33, Paul wrote:
Davey wrote:
On Sat, 20 Jun 2020 01:08:17 +0100
Cursitor Doom wrote:

On Fri, 19 Jun 2020 22:01:06 +0100, Jeff Layman
wrote:

That's more-or-less correct. It's to do with the maximum stable
amount of their oxide reacting with water. For sulphuric acid, it's
about 98% sulphur trioxide content; for nitric acid about 73%
nitrogen dioxide content. Both can "dissolve" further amounts of
their oxides, but they are not stable, and form fuming sulphuric and
fuming nitric acid. Hydrochloric acid is simply a solution of
hydrogen chloride in water - it does not react with the water in the
same way that the oxides do.
ISTR that the problem with hydrochloric is it forms an azeotropic
mixture at a relatively low concentration which makes further
purification very difficult. I don't think that occurs with the other
common mineral acids.

I once worked at an aircraft wing treatment plant, and one of the tanks
contained a mixture of hydroflouric, nitric and chromic acids. Heated
to 140 deg. F. The sump under the circulating pumps contained a sludge
which indicated on the pH test paper at less than 0 pH.

What was the tank made out of ?

Â*Â* Paul

What were the pump and glands made out of !

On 19/06/2020 20:56, Tim Streater wrote:


Don't spill this: https://en.wikipedia.org/wiki/Chlorine_trifluoride

Very interesting, had not come across that before. I love this quote:

"For dealing with this situation, I have always recommended a good pair
of running shoes"

On 20/06/2020 08:48, Jeff Layman wrote:
On 19/06/20 22:14, Cursitor Doom wrote:
On Fri, 19 Jun 2020 14:09:42 -0400, Paul
wrote:

Since ammonia is a watched substance, the bottle I had, I
can't buy another. That's the ****er of the thing.

I'm guessing this list of "watched substances" grows longer every
year. Is there an up-to-date list on the net anywhere?
Brick cleaner is strong hydrochloric acid. Diluted down, it makes a
very effective and dirt-cheap limescale remover; no scrubbing, just
dissolves it on contact forming a salt which is readily soluble -
being polar - in water and easily washed away.

If you have some food-based things (saucepans, etc) you want descaled
use a spoonful of food-grade citric acid in a small amount of boiling
water. You get calcium citrate, which is quite soluble. Citric acid is
strong enough to be quite effective at scale removal, but not too strong
as to attack metal.


Off at a tangent, steradent tablets are very good at removing severely
charred food from metal or enamelled cookware. Use minimum water.

On Sat, 20 Jun 2020 13:18:26 +0100, newshound wrote:

On 19/06/2020 20:56, Tim Streater wrote:


Don't spill this: https://en.wikipedia.org/wiki/Chlorine_trifluoride

Very interesting, had not come across that before. I love this quote:

"For dealing with this situation, I have always recommended a good pair
of running shoes"

and "It is also hypergolic with such things as cloth, wood, and test
engineers,"

Some substances are just plain frightening!
--
Peter.
The gods will stay away
whilst religions hold sway

On Sat, 20 Jun 2020 07:44:54 +0100, Jeff Layman
wrote:

On 20/06/20 01:21, Davey wrote:
On Sat, 20 Jun 2020 01:08:17 +0100
Cursitor Doom wrote:

On Fri, 19 Jun 2020 22:01:06 +0100, Jeff Layman
wrote:

That's more-or-less correct. It's to do with the maximum stable
amount of their oxide reacting with water. For sulphuric acid, it's
about 98% sulphur trioxide content; for nitric acid about 73%
nitrogen dioxide content. Both can "dissolve" further amounts of
their oxides, but they are not stable, and form fuming sulphuric and
fuming nitric acid. Hydrochloric acid is simply a solution of
hydrogen chloride in water - it does not react with the water in the
same way that the oxides do.

ISTR that the problem with hydrochloric is it forms an azeotropic
mixture at a relatively low concentration which makes further
purification very difficult. I don't think that occurs with the other
common mineral acids.

I once worked at an aircraft wing treatment plant, and one of the tanks
contained a mixture of hydroflouric, nitric and chromic acids. Heated
to 140 deg. F. The sump under the circulating pumps contained a sludge
which indicated on the pH test paper at less than 0 pH.

I'm surprised you had time to read the pH before the test paper
dissolved! What was that acid mixture needed for?

A *seriously* nasty cocktail, that is. None of them are pleasant, but
the HFl acid can burn through the skin and tunnel through your bones
regenerating its toxicity as it goes. Tissue necrosis and amputation
are inevitable without extremely quick and effective intervention. The
stuff of nightmares.

On Sat, 20 Jun 2020 13:20:43 +0100, newshound
wrote:

Off at a tangent, steradent tablets are very good at removing severely
charred food from metal or enamelled cookware. Use minimum water.

Charred food?? Barbecues? Charred meat is carcinogenic. Delicious
perhaps, but carcinogenic.

On 19/06/2020 19:30, The Natural Philosopher wrote:
On 19/06/2020 19:15, Tim Streater wrote:
On 19 Jun 2020 at 19:09:42 BST, Paul wrote:

Mike McLeod wrote:
Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?

cheers,
Mike

Just take the concentration on the bottle as
accurate, do the maths for dilution by volume,
to get it to where you want.

"Why is acid always added to water, and not the reverse"

I thought that was only the case for sulphuric?

I used to swallow the blotting paper as it came


I hope you didn't drop it.

On Friday, 19 June 2020 19:09:46 UTC+1, Paul wrote:
Mike McLeod wrote:
Hi,

Go to a builders' suppliers or a plumbers' merchants and you can buy
concentrated sulphuric and concentrated hydrochloric acid. Sulphuric
is concidered concentrated at 98% or more; hydrochloric at only about
35% IIRC. Nitric, OTOH, is concentrated at 73% or thereabouts so it's
all very confusing.
What's the best way to measure the strength of these acids in
practice, though? would a hydrometer do it?

You won't have the glassware to do a titration
(volumetric flasks, gram scale, burette, phenolphthalein,
beakers).

no need, just use a dropper & any acidproof container sat on dealer's scales.

On Sat, 20 Jun 2020 07:44:54 +0100
Jeff Layman wrote:

On 20/06/20 01:21, Davey wrote:
On Sat, 20 Jun 2020 01:08:17 +0100
Cursitor Doom wrote:

On Fri, 19 Jun 2020 22:01:06 +0100, Jeff Layman
wrote:

That's more-or-less correct. It's to do with the maximum stable
amount of their oxide reacting with water. For sulphuric acid,
it's about 98% sulphur trioxide content; for nitric acid about 73%
nitrogen dioxide content. Both can "dissolve" further amounts of
their oxides, but they are not stable, and form fuming sulphuric
and fuming nitric acid. Hydrochloric acid is simply a solution of
hydrogen chloride in water - it does not react with the water in
the same way that the oxides do.

ISTR that the problem with hydrochloric is it forms an azeotropic
mixture at a relatively low concentration which makes further
purification very difficult. I don't think that occurs with the
other common mineral acids.

I once worked at an aircraft wing treatment plant, and one of the
tanks contained a mixture of hydroflouric, nitric and chromic
acids. Heated to 140 deg. F. The sump under the circulating pumps
contained a sludge which indicated on the pH test paper at less
than 0 pH.

I'm surprised you had time to read the pH before the test paper
dissolved! What was that acid mixture needed for?


Some part of the treatment process for a military aircraft wing.

--
Davey.

On Sat, 20 Jun 2020 14:52:05 +0100
Cursitor Doom wrote:

On Sat, 20 Jun 2020 07:44:54 +0100, Jeff Layman
wrote:

On 20/06/20 01:21, Davey wrote:
On Sat, 20 Jun 2020 01:08:17 +0100
Cursitor Doom wrote:

On Fri, 19 Jun 2020 22:01:06 +0100, Jeff Layman
wrote:

That's more-or-less correct. It's to do with the maximum stable
amount of their oxide reacting with water. For sulphuric acid,
it's about 98% sulphur trioxide content; for nitric acid about
73% nitrogen dioxide content. Both can "dissolve" further
amounts of their oxides, but they are not stable, and form
fuming sulphuric and fuming nitric acid. Hydrochloric acid is
simply a solution of hydrogen chloride in water - it does not
react with the water in the same way that the oxides do.

ISTR that the problem with hydrochloric is it forms an azeotropic
mixture at a relatively low concentration which makes further
purification very difficult. I don't think that occurs with the
other common mineral acids.

I once worked at an aircraft wing treatment plant, and one of the
tanks contained a mixture of hydroflouric, nitric and chromic
acids. Heated to 140 deg. F. The sump under the circulating pumps
contained a sludge which indicated on the pH test paper at less
than 0 pH.

I'm surprised you had time to read the pH before the test paper
dissolved! What was that acid mixture needed for?

A *seriously* nasty cocktail, that is. None of them are pleasant, but
the HFl acid can burn through the skin and tunnel through your bones
regenerating its toxicity as it goes. Tissue necrosis and amputation
are inevitable without extremely quick and effective intervention. The
stuff of nightmares.

The contents of the tank were occasionally pumped to a storage tank
while the treatment tank was worked on. When the stuff was returned, it
came out of a pipe connection at the bottom of the tank, in a red
steaming fountain a couple of feet high. Impressive!

--
Davey.

On Fri, 19 Jun 2020 20:33:18 -0400
Paul wrote:

Davey wrote:
On Sat, 20 Jun 2020 01:08:17 +0100
Cursitor Doom wrote:

On Fri, 19 Jun 2020 22:01:06 +0100, Jeff Layman
wrote:

That's more-or-less correct. It's to do with the maximum stable
amount of their oxide reacting with water. For sulphuric acid,
it's about 98% sulphur trioxide content; for nitric acid about 73%
nitrogen dioxide content. Both can "dissolve" further amounts of
their oxides, but they are not stable, and form fuming sulphuric
and fuming nitric acid. Hydrochloric acid is simply a solution of
hydrogen chloride in water - it does not react with the water in
the same way that the oxides do.
ISTR that the problem with hydrochloric is it forms an azeotropic
mixture at a relatively low concentration which makes further
purification very difficult. I don't think that occurs with the
other common mineral acids.

I once worked at an aircraft wing treatment plant, and one of the
tanks contained a mixture of hydroflouric, nitric and chromic
acids. Heated to 140 deg. F. The sump under the circulating pumps
contained a sludge which indicated on the pH test paper at less
than 0 pH.

What was the tank made out of ?

Paul

Stainless steel, with a rubber lining. Which leaked occasionally,
until all the joints were sealed. No idea on SS grade etc.

--
Davey.