00:01
Hello, today we're doing problem 42 from chapter 4.
00:04
So we want the molar concentration of ions, the total molar concentration of ions, assuming complete dissociation of 0 .75 molar k2 -co3, and 0 .35 -m molar al -cl3.
00:20
So let's get at this.
00:22
First thing we have to do is write out the dissociation reaction.
00:27
So we have k2, so we need two k -k -plus ions.
00:31
And then we have 1 co3 plus 1 co3, 2 minus for the charge.
00:39
So we know that 1k2 co3 is going to make 2k plus ions and 1 co3 minus.
00:47
So what we have to do is take this concentration, multiply it by 2 for the k plus ions, and then we're going to add the concentration of the co3 -2 minus.
01:05
This is a 1 to 1 ratio.
01:07
So this is just going to be 0 .75.
01:13
And this is going to give us our final answer of 2 .25 molar.
01:23
And that's how we figure it out for any reaction.
01:27
You write the dissociation.
01:28
Well, you don't have to write it out...