Acid Concentration

[BenSon]

Ok I got some car battery sulfuric a while ago and today I needed some hydrogen so I dumped a nail it 25ml. Well after I got the Hydrogen I needed I decided to leave the nail in there to see how much it would disolve. Here I am about 6 hours later and the nail is still moderately reacting. How concentrated do you think this acid is? The nail was not galvanised and it has been sitting at room temperture all day. I did some very rough calculations when I first got it and worked it to be about .4mol/L althought this calc was done rushidly and poorly. I can't be arsed titrating it so can anyone give me an idea on how conentrated you think it will be?

 

~Scott

[raivo]

Impossible to tell. Even very diluted sulfuric acid will react with iron. You do not need burettes or anything to measure conc in your home lab. Any graduated cylinder or pippete gives acceptable precision.

 

You just need to know how much alkali is needed to neutralize known amount of your acid. Thats easy and there is no other way.

 

One more idea: you can collect all hydrogen from your experiment and compute amount of sulfuric acid by hydrogen volume.

[budullewraagh]

the idea iwth collecting hydrogen isn't particularly practical, as there will be other gases mixed with the hydrogen when it is collected.

 

try a titration.

[BenSon]

Well I bit the bullet and titrated it with a syringe. The verdict is 3.75mol/L, thats sounds more like battery acid, then a wimpy 0.4

 

~Scott

[woelen]

Ok I got some car battery sulfuric a while ago and today I needed some hydrogen so I dumped a nail it 25ml. Well after I got the Hydrogen I needed I decided to leave the nail in there to see how much it would disolve. Here I am about 6 hours later and the nail is still moderately reacting. How concentrated do you think this acid is? The nail was not galvanised and it has been sitting at room temperture all day. I did some very rough calculations when I first got it and worked it to be about .4mol/L althought this calc was done rushidly and poorly. I can't be arsed titrating it so can anyone give me an idea on how conentrated you think it will be?

 

~Scott

Do not let the speed of the reaction mislead you. Many metals, which react with acids, according to the electropositive series, do so very slowly. I have tried with iron, chromium, titanium, tin, etc. All react very slowly, even in 30% HCl or 30% H2SO4. Even zinc is not that fast. The only real fast one I found is magnesium and with some patience, aluminium also can be made to react fast in concentrated acids. Of course the alkali metals also are really fast.

[BenSon]

Do not let the speed of the reaction mislead you. Many metals, which react with acids, according to the electropositive series, do so very slowly. I have tried with iron, chromium, titanium, tin, etc. All react very slowly, even in 30% HCl or 30% H2SO4. Even zinc is not that fast. The only real fast one I found is magnesium and with some patience, aluminium also can be made to react fast in concentrated acids. Of course the alkali metals also are really fast.

I wan't realy surprised by the violence of the reaction more by how long it has been going for still moderately bubbling after 10 hours. But I am less surprised now that I found it to be 3.75mol/L

 

~Scott

[akcapr]

iron reacts quite slowly with acids, unlike zinc for example wich reacts fast(relitively).