Australia's Science Forum

Hello

I am very new to being a "Labbie".

Could anyone please tell me the amount/weight of sodium thiosulfate required to make 0.250M.

ps. I really need to take maths class again.

Cheers
Zali

62.04gm in 1 lt hope that helps

To make a molar soln write this formula down for future use

g=M x V x MW (grams = Molar x Volume x Molecular weight)

So for your example- you want a 0.25M soln made to 1 litre of sodium thiosulphate that has a MW of 248.18

so therefore

g= 0.25 x 1 x 248.18
g= 62.04g

so you will need 62.04g of sodium thiosulphate to 1 litre of water

I hope this helps

Thanks it did and went well

http://www.sigmaaldrich.com/chemistry/s ... lator.html
http://www.sigmaaldrich.com/chemistry/s ... lator.html
http://www.sigmaaldrich.com/chemistry/s ... lator.html
these links are useful for new people if I can send it too you via chamtalk

I have the app on my phone and it's very handy!!

What app?

Click on the above link then to your right is the app store.

Cool! Never paid attention to that before. I'm getting it!

Thank you smiley it will help out and I did not notice it when I opened the link.

As a newbie too, everyday I log on to here and get some many useful and helpful tips! Thanks everyone for sharing your expertise!!

Hi everyone, do you ever add sodium hydroxide when making up sodium thiosulfate? I made up a 0.2 M solution the straightforward way, 31.6 g in 1 L H2O, and my colleague who has been doing the job for more than 15 years said the proper way was to add 0.8 g of NaOH but she couldn't say why.

I did a google search and came across the use of sodium thiosulfate with NaOH in a titration prac which mentioned that solutions less than 0.1 M are unstable. I was wondering if this is a standard practice across all concentrations?

As with Copper Sulfate, you add an acid, it help keeps it longer, and much more stable. These are the tricks you learn along the way, so to speak of.