weak acids/bases

[nacho]

If you look at pH curves,
it is evident that in the presence of a basic solution (or a base, please correct me if i am wrong), an acid will go to complete ionisation (as long as the base is present) be it strong or weak and vice versa.
I didn't realise this.
So does that mean,
if in the event of someone being exposed to a strong acid or base, it is wiser to use a weak base/acid to neutralise this, rather than a strong one (orange juice anyone?)

[pi]

So does that mean,
if in the event of someone being exposed to a strong acid or base, it is wiser to use a weak base/acid to neutralise this, rather than a strong one?

As far as I'm aware, that would be correct (I have the same logic sequence as you on this one). If I was exposed to 4M HCl, I wouldn't want 4M NaOH put on me too...

[nacho]

So does that mean,
if in the event of someone being exposed to a strong acid or base, it is wiser to use a weak base/acid to neutralise this, rather than a strong one?

As far as I'm aware, that would be correct (I have the same logic sequence as you on this one). If I was exposed to 4M HCl, I wouldn't want 4M NaOH put on me too...

cool,
i just remember the year 10 science teacher, (or was it year 11 chem teacher) saying that when someone goes to a hospital with unknown acid/base burns
the doctors/nurses check the strength of the acid/base by adding a stronger base/acid one after another

Moderator action: removed real name, sorry for the inconvenience

[pi]

But I'm not entirely sure, we need one of the Chem pros to check this one out.

I remember that in a safety section of our prac booklets, we are always advised to rinse areas where spillage of acids have occurred with water (as it is a weak acid/base -being amphiprotic?)

[huaxiadragon]

But I'm not entirely sure, we need one of the Chem pros to check this one out.

I remember that in a safety section of our prac booklets, we are always advised to rinse areas where spillage of acids have occurred with water (as it is a weak acid/base -being amphiprotic?)

Well to be correct

The standard procedure is to rinse the area with
POWDERED weak acid/base as even weak acid and bases may cause unpleasantness.
powdered so the other healthy areas won't be affected by the additional acid/base

Moderator action: removed real name, sorry for the inconvenience

[Mao]

Say the scenario is you have some strong acid on you, like HCl.

You don't want to use a similarly strong base because you won't be adding it in stoichiometric ratio, you will be adding the base in excess. This implies after 'neutralization', you now have strong base on you, and we're back to the same problem.

For small volumes spilled on skin/other body parts, we tend to just use water to dilute it (that is, running water). This is not because water is amphiprotic, this is simply saying dilute acid is nowhere near as dangerous as concentrated acid. You won't be using powdered substance (for instance, you won't rub NaHCO3 powder on your arm if you spilled some acid. You run it under water to wash it off, then see a doctor if a horrible rash persists)

For larger spills on the ground, like breaking a large beaker/jar full of concentrated acid or base, you would use the amphoteric powder NaHCO3 (weakly basic) to cover the spill, safely neutralizing any acid/base, and gives a convenient method of disposal.


In VCE you don't get to see many strong acids or bases. Conc sulfuric acid would be the only strong chemical you would use, and it is generally handled by a supervisor/teacher, only only in drop-quantity by students. Dealing with 1M solutions or thereabouts is generally low risk (like 1M NaOH or 2M HCl) [that is if your head is screwed on and you don't try to drink any of it]. In the future, you'll learn to use actual safety precautions when dealing with chemicals like 1:1 SO3/H2SO4 (very strong acidic mixture with a lot of acidic vapour) and alkoxides (very strong bases).

[shinny]

Apparently adding water to a very strong acid like sulfuric and hydrochloric acid isn't a good idea though because it's a highly exothermic reaction, leading to burns and such. In these cases, apparently adding a weak base (lime or soap is recommended) actually does help since it prevents this burn.

EDIT:

In VCE you don't get to see many strong acids or bases. You don't get to see the strong guys until second year uni actually. Conc sulfuric acid is generally handled by a supervisor/teacher, not by the student. Dealing with things around 1M or less is generally low risk, that is if your head is screwed on and you don't try to drink any of it.

My brother washed his hands in 1M HCl by accident. Someone put it inside the typical distilled water bottles for some reason. His hands were perfectly fine though except for some itchiness.

[nacho]

Apparently adding water to a very strong acid like sulfuric and hydrochloric acid isn't a good idea though because it's a highly exothermic reaction, leading to burns and such. In these cases, apparently adding a weak base (lime or soap is recommended) actually does help since it prevents this burn.

Oh, i see.
Would this [exothermic reaction] be covered in unit 4? I have not come accross it as of yet in unit 3.

[shinny]

Apparently adding water to a very strong acid like sulfuric and hydrochloric acid isn't a good idea though because it's a highly exothermic reaction, leading to burns and such. In these cases, apparently adding a weak base (lime or soap is recommended) actually does help since it prevents this burn.

Oh, i see.
Would this [exothermic reaction] be covered in unit 4? I have not come accross it as of yet in unit 3.

You mean the concept of exothermic reactions? Or do you mean the equation itself. Well either way, yeh it'll be in unit 4.

[Mao]

Apparently adding water to a very strong acid like sulfuric and hydrochloric acid isn't a good idea though because it's a highly exothermic reaction, leading to burns and such. In these cases, apparently adding a weak base (lime or soap is recommended) actually does help since it prevents this burn.

yes, this would be the case for larger spills on the body. But most spills of conc acids/bases would only be drop-sized, which wouldn't generate nearly enough heat against a running tap to burn the victim. It is however a different case for solids (like powdered NaOH in fight-club), washing those spills with water would be a majorly bad idea.

And NaOH makes the skin way itchier than HCl, that and your hands become very slippery so you can't even scratch it.

[shinny]

It is however a different case for solids (like powdered NaOH in fight-club), washing those spills with water would be a majorly bad idea.

THE FIRST RULE OF FIGHT CLUB IS YOU DO NOT TALK ABOUT FIGHT CLUB.

[pi]

And NaOH makes the skin way itchier than HCl, that and your hands become very slippery so you can't even scratch it.

Did that to a finger in a titration in year 10 (that I did at home using primitive equipment and cabbage juice as the indicator). It also bleaches kitchen benches, much to my dismay...

[nacho]

It is however a different case for solids (like powdered NaOH in fight-club), washing those spills with water would be a majorly bad idea.

THE FIRST RULE OF FIGHT CLUB IS YOU DO NOT TALK ABOUT FIGHT CLUB.

so are we going to ban mao from vn or what? lol

[SpanishPear]

NEVER NEVER NEVER NEVER NEVER NEVER NEUTRAILSE A ACID/BASE SPILL ON YOUR SKIN
Neutralisation is an EXOTHERMIC, and pouring a strong Acid/base on your hand will not only burn you, but it will produce lots of heat!!
this is very important to understand.
Neutralise a spill ONLY if on a surface.
If a spill is on a skin, dilute with water as someone said above.

[Sine]

NEVER NEVER NEVER NEVER NEVER NEVER NEUTRAILSE A ACID/BASE SPILL ON YOUR SKIN
Neutralisation is an EXOTHERMIC, and pouring a strong Acid/base on your hand will not only burn you, but it will produce lots of heat!!
this is very important to understand.
Neutralise a spill ONLY if on a surface.
If a spill is on a skin, dilute with water as someone said above.

good advice but all those guys are 24+ now

locked thread