00:01
Redox is short for reduction oxidation mass reaction reactions which is a reaction that always comes in pair.
00:08
So in this case, we're going to balance the redox reaction shown to us and we will do this by hat reaction method.
00:17
In this method, we 're going to separate first these equations into two hat reactions by combining common species.
00:27
So first we separate, we do i2 with i03 - so and the remaining is cr2o7, cr3.
00:39
So the decision as to how to separate it this way is because of the common species.
00:44
So i2 on the left should have also i on the right so the only i, the only species that has i is the i03 - and so on.
00:53
Okay so once again this is separating two hat reactions.
00:59
Next we're going to balance the number of atoms aside from oxygen and hydrogen.
01:08
So in the first equation, we have to balance i, then on the second equation, we have to balance cr.
01:18
So to balance it, we have to put two in front of i03 since we need two iodine on that side and we also have to put two in front of cr on the right side of the second equation since we need two cr on that side.
01:35
We're going to balance now the oxygen by adding water on the side that needs to increase in the number of oxygen.
01:43
To do that, for the first equation, we have already six oxygen on the right hand side.
01:54
To make six also on the left hand side, we have to add 6 h2o.
02:00
And then on the second equation, we have seven oxygen on the left side or yes on the left side so we have to add 7 h2o on the right side.
02:13
We have to balance also the h since adding h2o introduces hydrogen.
02:19
So to do that, we have to add hydrogen in the form of h+.
02:23
So we have 12 h in the left hand side of the first equation so we need also the same number of hydrogen on that on the right side so we put 12 h+.
02:35
On the left side of the first equation, there is a second equation, there is no hydrogen but on the right side we have 14 so we need to put 14 on that side.
02:49
Next, we have to balance the charge.
02:52
So to balance the charge, we have to put electrons on the side that we need increase or we need a decrease on the total charge.
03:00
So let's count first the charge on the left side of the first equation.
03:04
We have zero since both are neutral and we have negative 2 plus 12 that's going to be positive 10 on the right side of the first equation.
03:15
In the second equation, we have negative 2 plus 14 that's 12 and on the right side we have 2 times 3 that's plus 6.
03:24
So we're going to bring down the charge on the first on the right side of the first equation from 10 to 0.
03:33
The way to do that is to add 10 electrons...