[wala01]

Alright well, i'm doing an experiment that basically tests for the amount of sulfur dioxide in dried apricots. What i'm doing is blending the apricots and mixing it with water and titrating iodine into that solution. My problem is, i don't have much of the iodine needed for the experiment and i want to know if i need to order more iodine before i start.

Here is the data given to me to do the calculations: I tried it, but i'm not sure if this is correct or not. It would be great if you guys could help me out (:

So here are the half equations i came up with:

SO₂ + 4H+ + 4e- -> S + 2H₂O
2I- -> I₂ + 2e-           
SO₂ + 4H+ + 4I- -> S + 2I₂ + 2H₂O

It tells me that the maximum sulfur dioxide content of dried apricots is 3.000g of SO₂ per kg of apricots. In 20g of apricots, this translates to .06g of SO₂ in 20g of apricots.

Which is .000938 mols (mols = mass/molar mass.     mols = .06/64)
The mole ratio of SO₂ to I₂ is 1:2
So, 0.000938:0.001875.

The volume of I₂ needed to reach an endpoint was then calculated to be 48mL... Is this correct?
V= n/C     C of I₂ is 0.01g of iodine in each mL, which is .000039mol per mL
So V = 0.001875/.000039 = approx. 48mL.

[Borek]

So here are the half equations i came up with:

SO₂ + 4H+ + 4e- -> S + 2H₂O
2I- -> I₂ + 2e-           
SO₂ + 4H+ + 4I- -> S + 2I₂ + 2H₂O

Huh?

You said you titrate with iodine, not with iodide.

[wala01]

oh my bad... so... then i have

I₂ + 2e^-  2I^-
SO₂  SO₄^2- + 2e^-   ?

With this i would get I₂+SO₂  2I^- +SO₄^2-

Now the ratio between I₂ and SO₂ will only be 1:1?

And the final volume i would need will be approx 24mL

[Borek]

With this i would get I₂+SO₂  2I^- +SO₄^2-

This is not balanced yet. But ratio should not change after balancing.

And yes, around 24 mL per 0.06g of SO₂.