Test Index

NCERT Class XII Chemistry
Chapter - Solutions
Questions with Solutions

© examsnet.com
Question : 16
Total: 53
Heptane and octane form ideal solution. At 373 K, the vapour pressure of the two liquid components are 105.2 kPa and 46.8 kPa respectively. What will be the vapour pressure of a mixture of 26.0 g of heptane and 35.0 g of octane?
Solution:  
Molar mass of heptane (C7H16)=100 g mol−1
Molar mass of octane (C8H18 )=114g mol−1
Number of moles of heptane =
26.0 g
100 g mol−1
=0.26 ‌mol
No. of moles of heptane =
35.0 g
114 g mol−1
=0.31 ‌mol
x (heptane )=
0.26
0.26+0.31
=0.456
x (octane )=1−0.456=0.544
x (octane )=1−0.456=0.544
p( heptane )=0.456×105.2 ‌kPa=47.97 ‌kPa
p( octane )=0.544×46.8 ‌kPa=25.46 ‌kPa
PTotal=47.97+25.46=73.43‌kPa
© examsnet.com
Go to Question:
Prev Question
Next Question