Sciencemadness Discussion Board

dilution of sulfuric acid

hardik22 - 23-1-2018 at 02:52


I want to dilute sulfuric acid from 98%w/w to 84%w/w..
how much temperature will rise and fumes generated ?

Please suggest me right method

LearnedAmateur - 23-1-2018 at 03:33

I assume you’ve calculated how much water you need for the amount of H2SO4 you wish to dilute. Slowly add the acid to the water in an ice bath - if you only want to dilute less than 50mL of acid then you shouldn’t need active cooling but still keep it slow, in 1mL portions every 30-60 seconds. When I’ve diluted H2SO4 (20mL to 10mL water), the temperature increases to about 50-60 degrees C and it holds its temperature for a lot longer due to a lower standard heat capacity relative to pure water.

I’ve never had any experience with fumes when diluting, and if there are any then it’ll be mostly steam. Not hazardous on this scale, but I can imagine it would be a lot worse if you’re working with industrial quantities or something.

If you were to add water to acid, it releases a lot more heat since concentrated H2SO4 is a dehydrating agent and can even cause a rapid boil, throwing hot, corrosive droplets everywhere. Slowly adding the acid helps to keep the temperature down since it’s easier to dissipate, and make sure that there is plenty of stirring/mixing since H2SO4 tends to sink and form a layer under the water, which will cause a sudden spike in temperature if allowed to mix.

Overall, it’s not a majorly hazardous procedure and should be quite easy for someone with chemistry experience.

hardik22 - 23-1-2018 at 04:28


I have large Quantity of H2SO4 which is 4800 kg/hr.

Ubya - 23-1-2018 at 04:58

Quote: Originally posted by hardik22  

I have large Quantity of H2SO4 which is 4800 kg/hr.


you need to dilute 4.8 tons in an hour?
not really amateur scale

LearnedAmateur - 25-1-2018 at 06:40

Yeah I was thinking up to several litres, definitely not on the order of tonnes. Although some members here have some industrial experience, this forum is more for the small and intermediate scale chemistry which can be far different (in terms of reaction properties at the least, safety also) compared to industry manufacture. I can guarantee that you’ll find more appropriate information and answers by looking elsewhere - not that this forum won’t help, but I feel as if there is some risk of erroneous information simply due to lack of appropriate experience, as with my answer.

aga - 25-1-2018 at 08:59

Assuming 1.84g/ml, that works out at 0.724 litres per second !

Basically you need the detailed plans for an entire processing plant rather than simple advice on how to dilute the acid.

NEMO-Chemistry - 25-1-2018 at 09:22

4800Kg/hr in India?? Hmm......... You might want to look up the chems companies in India and take a peek at the output ;)

happyfooddance - 25-1-2018 at 10:24

I like to pour it over crushed ice. It takes a little stirring but you don't have to add in portions.

Obviously the starting temp of both components is a factor so think along those lines for your purpose.