A phase diagram of temperature versus composition for a mixture of the two volatile liquids octane (bp = and decane (bp = 126°C)is shown.
-Assume that you start with a mixture containing 0.80 mol of decane and 0.20 mol of octane,at what approximate temperature will the mixture begin to boil?
A)temperature at point a
B)temperature at point b
C)temperature at point d
D)temperature at point f

Question

A phase diagram of temperature versus composition for a mixture of the two volatile liquids octane (bp =  and decane (bp = 126°C)is shown. 
-Assume that you start with a mixture containing 0.80 mol of decane and 0.20 mol of octane,at what approximate temperature will the mixture begin to boil?
A)temperature at point a 
B)temperature at point b 
C)temperature at point d 
D)temperature at point f

Quizplus · Accepted Answer

At point b, the mixture is at the boiling point (vapor pressure = atmospheric pressure) and the composition is approximately 0.20 mol of decane and 0.80 mol of octane. Therefore, when we start with a mixture containing 0.80 mol of decane and 0.20 mol of octane, it will begin to boil at approximately the temperature at point b.

A Phase Diagram of Temperature Versus Composition for a Mixture