Answer:
The mass of KF in the mixture is 2.77 gms.
Explanation:
Given;
Total weight of mixture (LiF+KF)=5.32gms
Let, mass of KF in the mixture = x gms
⟹ mass of LiF in mixture =(5.32-x)gms.
We know that :
Atomic weight of F=19gms.
Atomic weight of Li =7gms.
Atomic weight of K = 39 gms.
moles=mass/(molecular weight)
Thus, moles of KF=x/58
and moles of LiF = (5.97-x)/26LiF=(5.97−x)/26
Thus,
moles of F in KF=moles of KF=x/58 ---(1)
moles of F in LiF =moles of LiF= (5.32-x)/26---(2)
From (1) & (2),
Total moles of Fluorine
=(x/58)+((5.32-x)/26)
Hence,
total weight of Fluorine in sample = moles*Atomic weight
=((x/58)+((5.32-x)/26))*19gms.
=3.12 gms.---(given)
Now, solving the equation for x,
26x +(5.32*58)-58x
=3.12*58*26/19
22x=308.56-247.62
x=60.94/22
=2.77 gms. (Answer)
Thus, the mass of KF in the mixture is 2.77 gms.
