Question

The variation of vapour pressure (b) as a function of temperature (a) is studied for $C_2{H}_{5}O{C}_2{H}_5,CC{l}_4,and{H}_{2}O$ at 760mm Hg and is shown in the figure below. The boiling temperature of $C_2{H}_{5}O{C}_2{H}_5,CC{l}_4,and{H}_{2}O$ are 308,350 and 373K respectively. Curves A,B, C respectively correspond to:

• A. $H_{2}O,C_2{H}_{5}O{C}_2{H}_5,CC{l}_4$
• B. $C_2{H}_{5}O{C}_2{H}_5,CC{l}_4,H_{2}O$
• C. $CC{l}_4,C_2{H}_{5}O{C}_2{H}_5,H_{2}O$
• D. $CC{l}_4,H_{2}O,C_2{H}_{5}O{C}_2{H}_5$

Answer 1

The correct option is C $CC{l}_4,C_2{H}_{5}O{C}_2{H}_5,H_{2}O$

Boiling point is the temperature at which the vapour pressure is equal to the atmospheric pressure. So, the right most compound would have the highest boiling point, the left most the least. The order of boiling points from the graph is:

$C>A>B$ so $A,B,C$ are $CC{l}_4,C_2{H}_{5}O{C}_2{H}_5,H_{2}O$ respectively.