Question

answer number three please using the equation provided. I dont understand. thanks!

21'(aq) + 2NO2 (aq) + 4H(aq) - 12(aq) + 2NO(aq) + 2H2O(1) [Eq. 3] (Note from this equation, that in the experiment, the number of moles of iodide ion present is twice the number of moles of iodine that will be determined by the absorbance measurements. That is, the mole ratio of 12:I" is 1:2. You will not need to account for this mole ratio explicitly, if you correctly calculate the concentrations of your calibration standards as described below.)

Answer 1

Yes, this is a redox reaction.

A redox reaction is a reaction in which the change in oxidation state can be seen, this is because of the reason that the chemical reaction involves the transfer of electrons from one species to another.

In the above equation, we can see that at the left-hand side i.e the reactant side, is having I-, which is being converted to I2 by losing the electrons.

2 I- → I2

I-, has the oxidation state -1, and I2 , is having Zero.

It means there is oxidation(loss of electrons) that occurred, as the oxidation state is increased (from -1 to 0), so, Iodine is said to be oxidized.

and Now, considering other species,

2NO-2 → 2NO

Here, in the NO-2, the oxidation state of N is +3, and its +2 in NO.

We can see that there is a reduction(gain of electron) in the oxidation state(from +3 to +2). So, here N is reduced.

Hope this helps!