00:01
Okay, so in this problem we are trying to figure out the mass of n, a, b, r in grams.
00:06
So we can always set up a system of equations by adding in the mass of one mixture and adding in the mass of a second mixture, and we know that's going to come out to the total mass of the mixture combined.
00:24
And in this case we know that is going to be 2 grams.
00:29
2 .00 grams.
00:31
So in the case of this problem i'm going to let m1 represent the mass of n, a, c, l, and i'm going to have m2 be what we're trying to find out, the mass of n, a, b, r.
00:52
Now one other thing we know about this problem is that this mixture is going to contain 0 .75 grams of sodium, and we know that sodium or the n, a is going to come from both n, a, c, l and n, a, b, r.
01:07
So we need to set up an equation for the n, a or sodium content within the whole mixture.
01:14
So to do that we are going to say 0 .75 grams of sodium is equal to the mass fraction of our sodium in n, a, c, l.
01:36
We're going to multiply that by the mass of mixture one, and that is going to be added to the mass fraction of sodium in n, a, b, r.
01:52
And since that we labeled as m2, we're going to multiply that by m2.
01:58
So we know that the mass fraction of sodium in n, a, c, l is going to be the molar mass of sodium divided by the molar mass of n, a, c, l.
02:08
And we're going to do the same thing for n, a, b, r.
02:12
So we have 0 .75 grams sodium is equal to, and i'm going to use brackets to make this more clear, 23 grams per mole divided by 58 .5 grams per mole, and that whole thing is going to be multiplied by m1.
02:40
Then we're going to again do the same thing for n, a, b, r.
02:45
We have 23 grams per mole divided by 102, parenthesis, 102 .9 grams per mole, and that is going to be multiplied by m2.
03:04
So we can actually use this equation up here to find a substitute for m1 in this equation that we just created.
03:14
So if we manipulate this equation up here a little bit, we can say that m1 is equal to 2 grams minus m2.
03:28
So we are going to fill this in for m1 in this equation we just created down here...