naikii, STOP!!! color>size>
You can harm yourself.

Hi and thanks for your concern. I understand there is an element of risk involved and I have the necessary safety equipment like glasses, chemical gloves and coveralls to help reduce this risk. I don't wear any protective clothing at all when doing other daily activities with an element of risk, things as mundane as cooking for example, yet being splashed by boiling oil spat from the pot whilst deep frying can burn or blind as easily as acid.

Naikii, just remember that when mixing water and a strong acid always add the acid TO the water (never add water to the acid).

Strong acids like sulfuric acid rapidly protonate water (to make H3O+). This is exothermic so adding a small amount of water to excess acid can cause the water drop to flash boil and this can cause a splash of acid just like your water into hot oil example.

Thanks Rhino, someone pointed that useful information out in another thread as well, and it was something I didn't ever recall learning in chemistry (although I sure I was sleeping or something that lesson!). I am making up a much safer 10% stock solution to use later today, just waiting on a bunch of plastic pipettes to be delivered so I can accurately and safely transfer small amounts of concentrated acid.

naikii, I guess that I must have a masochistic streak.
A "no exception!" injunction was applied to "acid in a pipette". Always use a burette.
And you are planning to use plastic pipettes to suck up sulfuric acid?
Here is what I remember from Chemistry classes.
Little John is dead and gone;
He'll bother us no more.
For what he thought was H2O was H2SO4.
Please reply so that I will know that you are alive and well.

I am most definitely alive and well. From my memory of chemistry I was under the impression that most plastic can safely store sulphuric acid, and that concentrated sulphuric acid was activated more upon its contact with water than in its pure state.

I have 98% sulphuric, and will (soon) have 3ml, 15cm graduated plastic pipettes made from polyethylene LDPE, which according to this chart will suffer little to no damage even after 30 days of exposure to even strong acids, and 7 days for oxidising agents.

I will only need to use it for a matter of minutes. Its probably true that a burette is a better instrument, but for my level of accuracy required, and for the small amount of liquid I will be transferring, I think the pipette will function just fine. Afterwards it will be well rinsed in a lot of water to dilute any acid that remains in or on the pipette, and after it is very well washed I will drop it in a sodium bicarbonate solution to neutralise any remaining acid, before disposing of.

If you still believe that this has an unacceptable level of risk involved, I am open to suggestions for improvement, but considering that all the task really involves is transferring a small amount of concentrated acid without dripping, spilling or splashing it on anything, I believe I am more than capable.

For the record, I ended up doing something slightly different.

I got a 25L plastic drum with a tap on the bottom, and filled it with the full 25L of water. I then kitted up in full safety gear and slowly and carefully tipped the whole Litre of concentrated acid in. Earlier in the week I had used a spreadsheet to determine that about 16L of water was needed to dilute 1L of acid down to 10%, so being an extra 9L on top I am guessing that my acid is about 5-8% acid now, and quite safe to use.

To be doubly safe I even diluted this down again by 50% for the bottle I will be working with when acidifying tap water. Perhaps it is too weak, we shall find out tomorrow when I test it.

Just keep in mind that even at 5-10% sulfuric acid will cause burns. I am assuming that you made sure the plastic of the 25L drum is resistant to sulfuric acid, but even so you probably don't want to store it in the drum long term. Even plastics that are resistant can become brittle over time. Any spilled acid especially on the skin or (worse) clothing should be liberally sprinkled with baking soda and then rinsed/removed.

I am kind of concerned about the tap at the bottom of the drum. It likely has internal parts made of rubber or different plastics/metal that may not stand up to the acid. I would highly highly highly recommend that you put the drum into a secondary container so that in the case of a leak you will not have acid everywhere. If you are keeping in on the bare earth you may want to dig a little moat to control any runoff.

Also, sulfuric acid is not flammable but it can produce hydrogen gas when in contact with metal so be careful to store it somewhere ventilated and not near an ignition source.

Also also, you probably want to put a danger sign on it if you haven't already to alert any ne'er-do-wells.

Have fun!

Just for the record, if you start with 1 L of 98% and dilute it to a final volume of 26 L (1 + 25), then your new concentration will be 1/26 of 98%, which is slightly under 4%.

This will give you a pH of a little less than 1, which is still very acidic. To get the pH up near, say 5, which is around the pH of some acid rain, you will need to dilute your 4% solution by a factor of 10,000. That would be 1 mL of 4% added to 10 L of water. At this rate, you should have enough 4% acid to last you a very very long time.

This pH would likely not cause any leaf injury, but I don't know enough about it to say for sure.

ThinMan

Thanks thatâÂÂs a helpful post.

I am having trouble with my calculations, and you seem to have some chemistry knowledge, so can you spot where I went wrong? it has been many years, so I may have my method mixed upâ¦

If the initial solution is 98%w/w sulphuric which has a mass/volume of 1.84g/ml and I have 1000ml, I have 1840g sulphuric.

Water is 1g/ml, and I added 25000ml, thus 25000g.

Percent sulphuric in final solution = (1840/25000)*100= 7.36%

I apologize for the misdirection, and you are closer to the right percentage than I was. I had totally overlooked the fact that the 98% was v/v, and not w/v or v/v.

The only error I can see that you made was in using 25,000 g for your final mass, rather than 25,000 + 1840 = 26,840 g. (1840/26,840)*100 = 6.8% v/v.

This kind of confusion is why chemists are more fond of using molarity for a concentration unit, rather then percent.

The rest of what I said was pretty much on the money. To be a little more exact, the molarity of conc. H2SO4 is 18 M, and 1/26 of that is 0.69 M. This would give a pH of 0.14, which is pretty acidic indeed.

To dilute that to a pH of 5 would actually take about a 14,000-fold dilution: 1 mL of the 6.8% acid added to 14,000 mL (14 L) of water.

Sorry for the confusion in my first post. I appreciate your showing your calculation so I could see how you were thinking and how I had gone wrong.

ThinMan

Thanks! my working solution is diluted by about half again, so your original approx 1ml for 10L is probably pretty spot on.. I am waiting on litmus paper to arrive to be properly sure, but i think it is an excellent place to start.