Sulfuric acid percentage values and sodium bisulfate alternative?

[What About Bob]

I have scoured all around the forums and the web for any answers as to what the conversion would be to find percentage values for sulfuric acid. I always see sulfuric acid values in moles, "N" and other values. One exception that I have seen percentages are for the battery acid versions, 37%, 30%, etc. I have the math for breaking this down further to reach a 10% solution which will be added to a potassium permanganate bleach solution, per Ilford's instructions, but a part of me would prefer to try out sodium bisulfate instead. Amazon has the battery acid version that shows the percentage values but you have to buy like eight containers of the stuffI and I really don't want to stock sulfuric acid in big amounts which is why I was thinking to use the bisulfate instead.

So a question I would have is how would I determine the amount of bisulfate to use instead of a 10% solution of sulfuric acid?

I did read over a past post by Gerald who gave the math on the substitution but it was done in moles and not percentages. If anyone would have any directions where I could go to determine the values that would be great. Thanks.

 

[Raghu Kuvempunagar]

You need to use 4.42 g of Sodium Bisulphate (anhydrous) for every ml of concentrated Sulphuric Acid. So, if Ilford is recommending you to use 10 ml of concentrated Sulphuric Acid, then use 44.2 g of Bisulphate. But no harm will be done if you instead use 45 g if that's easier to weigh.

 

[What About Bob]

You need to use 4.42 g of Sodium Bisulphate (anhydrous) for every ml of concentrated Sulphuric Acid. So, if Ilford is recommending you to use 10 ml of concentrated Sulphuric Acid, then use 44.2 g of Bisulphate. But no harm will be done if you instead use 45 g if that's easier to weigh.

Thanks Raghu

My new gram scale measures out to two decimal places. Oddly It didn't come with a calibration weight so I have to hunt one down. All my other scales came with them.

 

[ags2mikon]

You can buy the battery acid from your NAPA or other auto parts stores in smaller sizes. I bought mine from O'Reilly auto parts for motorcycle batteries.

 

[What About Bob]

You can buy the battery acid from your NAPA or other auto parts stores in smaller sizes. I bought mine from O'Reilly auto parts for motorcycle batteries.

Thanks ags2mikon

I was pointed to a local AutoZone. I had to go to the MSDS sheet for extra information. The percentages listed in the sheet for this acid is 30-43%. It is by East Penn. I'm guessing it can be any one of those values. Would it be safe to say I can go in the middle and use 37% as original chemical value for the calculation?

I'm using: (percentage required for solution * total volume of solution / percentage of original chemical).

 

[ags2mikon]

Generally 30-32% for lead acid batteries. IIRC. I think I marked mine as 31%. I'm not near my darkroom now. Dilute by pouring the acid into the water not the other way. Gloves, face shield and appropriate PPE is in order. It is safe if you use caution, just like driving.

 

[koraks]

AFAIK the acidity of a permanganate bleach is not critical. For bleaches like these, I've always just used 'a dash' of something.

 

[Donald Qualls]

You can also buy concentrated sulfuric acid at home improvement stores, sold as a drain cleaner/opener. I have a bottle at home, purchased to make bleach for B&W reversal. It'll probably cost less for a pint-ish bottle than buying a box of battery acid sized for filling a dry charged car battery (if NAPA will even still sell theirs).

 

[koraks]

You can also buy concentrated sulfuric acid at home improvement stores, sold as a drain cleaner/opener.

Check the bottle before purchasing; the constituents of drain cleaner differ wildly across the globe and potentially with in the US as well. Around here, drain cleaner is virtually always sodium hydroxide.

 

[Donald Qualls]

Check the bottle before purchasing; the constituents of drain cleaner differ wildly across the globe and potentially with in the US as well. Around here, drain cleaner is virtually always sodium hydroxide.

At my local Lowe's the drain openers that aren't (pure or impure) sodium hydroxide are stored separately and they have enough SDS-type information to know what I'm buying. I used to get Red Devil Lye at the supermarket, but now I have to order a generic brand from Amazon.