Question

X gram urea Co(NH2)2 dalam 48,6 gram air, ternyata fraksi mol 0,01. harga x adalah....(Mr Urea = 60)

Answer 1

Mol urea = x / 60
Mol air = 48,6 / 18 = 2,7

Fraksi mol = mol urea / [ mol urea + mol urea ]
0,01 = [ x / 60 ] / [ x / 60 + 2,7 ] ---> dikali 100
[ 100x / 60 ] / [ x / 60 + 2,7 ] = 1
100x / 60 = x / 60 + 2,7
99x / 60 = 2,7
99x = 2,7 . 60 = 162
x = 162 / 99 
= 1,636363.....
≈ 1,64 gram ( nilai pendekatan )