Sodium Thiosulfate pentahydrate

[Mad Doc]

Hey! Not a chemist so I need a bit of help with a tiny issue, I have used Sodium Thiosulfate in the past for neutralising bleach and it was in large crystal form almost like carbon pellet shape, however I needed some now and ordered pentahydrate by mistake which is pretty much a powder form, my issue is that the recipe I’ve used and know is for the crystal form and I’m not sure if the mixing quantity is different for the pentahydrate, I’m kinda considering to just re-order but i have a kilo of the stuff now. Maybe someone can help? @Randy Holmes-Farley

 

[Randy Holmes-Farley Verified Community Expert]

Sodium thiosulfate pentahydrate (molecular weight = 248 g/mole) just has 5 extra water molecules in the crystal, relative to anhydrous sodium thiosulfate (molecular weight = 158 g/mole).

To use the former to get the same strength as the latter, you need to use 248/158 = 1.6 times as much.

 

[Mad Doc]

Sodium thiosulfate pentahydrate (molecular weight = 248 g/mole) just has 5 extra water molecules in the crystal, relative to anhydrous sodium thiosulfate (molecular weight = 158 g/mole).

To use the former to get the same strength as the latter, you need to use 248/158 = 1.6 times as much.

Thank you very much Randy!!! I’m assuming it should have no difference in the way it dissolves?

 

[Randy Holmes-Farley Verified Community Expert]

Thank you very much Randy!!! I’m assuming it should have no difference in the way it dissolves?

Dissolution might take a different amount of time, but the ions in solution after dissolution are identical.

 

[Mad Doc]

Dissolution might take a different amount of time, but the ions in solution after dissolution are identical.

Thank you couldn’t find any information on the above and it took you like 5 sec to figure it out so I’m very greatful!

 

[Randy Holmes-Farley Verified Community Expert]

Thank you couldn’t find any information on the above and it took you like 5 sec to figure it out so I’m very greatful!

lol

You’re welcome. Happy Reefing!

 

[Mad Doc]

Don’t wanna

lol

You’re welcome. Happy Reefing!

become a pain but just came across another issue which I thought would be the easiest part. I can’t seem to find household bleach 5% sodium hypochlorite the only ones I’m finding that are unscented describe it as containing 1g to 100g sodium hypochlorite whatever that means but doesn’t make sense to me. Definitely doesn’t seem like 5%. can that be used or try to find something better UK is pretty lame for certain things.

 

[Randy Holmes-Farley Verified Community Expert]

Don’t wanna

become a pain but just came across another issue which I thought would be the easiest part. I can’t seem to find household bleach 5% sodium hypochlorite the only ones I’m finding that are unscented describe it as containing 1g to 100g sodium hypochlorite whatever that means but doesn’t make sense to me. Definitely doesn’t seem like 5%. can that be used or try to find something better UK is pretty lame for certain things.

Do you have the exact ingredient description? Thats a ratio of ingredients, not the concentration. That’s probably sodium hydroxide and sodium hypochlorite .

 

[Mad Doc]

Do you have the exact ingredient description? Thats a ratio of ingredients, not the concentration. That’s probably sodium hydroxide and sodium hypochlorite .

That’s basically all there is on the bottle

 

[Mad Doc]

That’s basically all there is on the bottle

Also this was my other option but they both make no sense lol

 

[Randy Holmes-Farley Verified Community Expert]

I guess that first one is a concentration, but it seems very low at 1%. Use 5x as much of it as 5% bleach and you should be OK if you are using it in an application where it gets combined with additional water.

 

[Randy Holmes-Farley Verified Community Expert]

The second one is 1.5%.

 

[Mad Doc]

okay so if I’m correct this means I should use the Sodium thiosulfate as if I was using 5 times less bleach since I’m only doing it x5 coz of its strength?
If I need 20ml of bleach normally and then need 5ml of Sodium Thiosulfate to negate this, should I still use 5ml even tho I’m using 100ml of the 1% bleach or dose 25ml Sodium Thiosulfate instead?
P.S. I really do appreciate your help sir, thank you!

 

[Randy Holmes-Farley Verified Community Expert]

okay so if I’m correct this means I should use the Sodium thiosulfate as if I was using 5 times less bleach since I’m only doing it x5 coz of its strength?
If I need 20ml of bleach normally and then need 5ml of Sodium Thiosulfate to negate this, should I still use 5ml even tho I’m using 100ml of the 1% bleach or dose 25ml Sodium Thiosulfate instead?
P.S. I really do appreciate your help sir, thank you!

Yes, that’s what I would do.

 

[Mad Doc]

The second one is 1.5