Hi, I'm new here and having a little trouble with some coursework. If you could help, great! Basicly, to bring you upto speed, I've been planning an A2 investigation (if you're from anywhere but england, that just means an education stage between Highschool and Uni) and it requires an individual investigation.Questions are in bold for your viewing pleasure. Sorry it's so long.
Basicly to find out how much oxygen is in a sample:
1) Reacting manganese (II) hydroxide with water containing oxygen creates Manganese (III) hydroxideoxide.
2) React the Manganese (III) Hydroxide with Hydrochloric acid and Pottasium iodide, which willl create a whole heap of things, including Iodine.
3) titrate the iodine with sodium thiosulphate and you can find when there are no more Iodine molecules (as they turn into ions).In depth that means
O₂ (aq) + 4Mn(OH)₂ (s) + 2H₂O (l)
2Mn(OH)₃ (s) + 6HCl (aq) + 2KI (aq)
2MnCl₂(aq) + 2KCl (aq) + I₂ aq)+ 6H₂O (l)
Then a titration:
I₂ (aq) + 2Na₂S₂O₃(aq)
(aq) + 2NaI (aq) (Basicly when all the iodine has gone, that’s the end point)First off, does that sound like a plausable experiment? This is the big thing that needs addressing before ANYTHING else happens. I mean, would the reactions happen at all? It took some time to work this out!
Heres were it gets a little tricky.
I have at my resources:
1 mole of Manganese (II) Hydroxide in a 40:60 ratio with dilute water
1 mole of Hydrochloric acid in a 30:70 ratio with dilute water with 2 grams of Potassium Iodide
0.0125 mol dm³ sodium thiosulphate solution (2Na₂S₂O₃)
So I’m just wondering.. Doesn’t the 40:60 ratio just mean that the solution is reducing in molarity.. or am I just being a plank? (sorry if that's a bit numptyish.. It's been months since we revised anything on molar equations)!So that means the manganese(II)Hydroxide is actually 0.4 mols? and HCL 0.3?
I have a question about actually working out how much oxygen is actually in a sample.. but that's long and laborious and best not push my luck on a new forum!
Sorry for the wall of text on 2 simple questions.. but hopefully some of you can answer a few questions.. At least this isn't last minute before actually doing the coursework!
thankyou for reading - cheers!