00:01
Here a solution is made by mixing 10 grams of thiophene that is c4h4s and 80 grams of heptane that is c7h16 and calculate the mole fraction of thiophene.
00:16
So what we are going to use here the formulae right.
00:19
So what is mole fraction? mole fraction of thiophene is equals to moles number of moles of thiophene number of moles of thiophene upon total number of moles in the solution in the solution right so what we know we don't we don't know the value of number of moles right total number of moles that would be including number of moles of heptane as well so you can bifurcate this formula in the next part like this number of moles of thiophene let us say this is n1 and it is divided by number of moles of thiophene plus plus number of moles of heptane, right? this is n2, let us say.
01:51
Yes? can you see that? okay.
01:57
Now, what we know about the number of moles? we only know the mass.
02:02
So, since number of moles moles is given by mass upon molar mass, right? so what is the molar mass of thiophene and heptane? we can find out the number of moles.
02:20
Therefore, n1 would be equals to mass of thiophene is 10 grams and it is divided by molar mass.
02:30
What is the molar mass of thiophene which which is 84 grams per mole.
02:44
84 grams per mole, okay? so, it would be 10 by, it is in grams, right? grams, grams cancels out each other and we would be getting n1 is equals to 10 by 84 is nothing but, this would be 5 by 42 moles, yes? so, let us say this equation what we have calculated, is equation number 1, right? now, n2 is, and n2 is for heptane.
03:17
So, the mass is 80 grams here, and it is divided by heptane, right? so, what is the molar mass of heptane? it would be 100.
03:33
It would be 100 grams per mole.
03:38
Grams, grams cancel out each other.
03:40
N2 becomes equals to 80 by 100.
03:45
That makes it 4 by 5 or simply 0 .8 here.
03:53
Yes, so 0 .8 moles.
03:55
We got this value.
03:58
Simple...