2. A hypothetical phase diagram is show below, a- Find the melting points of sol
ID: 1819386 • Letter: 2
Question
2. A hypothetical phase diagram is show below, a- Find the melting points of solid A, solid B, solid AB and solid AB2. b- A liquid containing 10wt%B is cooled down slowly so that equilibrium prevails at each step. What solid will come out first and at what temperature and what is the composition of the last drop of liquid? At what temperature will the whole liquid solidify and what kind of solids are present and how much for each kind? c- A liquid containing 60wt%B is cooled down slowly. At what temperature will the whole liquid solidify and what solids are present and how much each? d- A liquid containing 90wt% B is cooled down slowly. Describe what happens along the way before the temperature reaches 600oC.Explanation / Answer
melting points of solid A is where curve meets when wt%B is 0...so it is around 930-940.
melting points of solid B is where curve meets when wt%B is 100...so it is around 830.
A liquid containing 10wt%B is cooled down slowly so that equilibrium prevails at each step.
then
pure A solid will come out first and at temperature around 910,temp can be found out by drawing line with composition %10 of B..where the upper curve intersects ..temp corresponding to that..
40% wt of B is the composition of the last drop of liquid..
At 760 temperature the whole liquid solidify ,
the kind of solids are present are mixture of pure A and AB...
by applying liver rule
if AB is solid with 51%wt of B, then
wt% of solid A =(51-10)/(51-0)=80.392%,
wt% of solid A =(10-0)/(51-0)=19.61%..
A liquid containing 60wt%B is cooled down slowly.
At around 730 temperature the whole liquid solidify
and the kind of solids are present are mixture of pure AB and AB2...
by applying liver rule
if AB is solid with 51%wt of B,
and AB2 is solid with 67%wt of B
then
wt% of solid AB =(67-60)/(67-51)=43.75,
wt% of solid AB2 =1-wt% of solid AB=1-43.75=56.25..
A liquid containing 90wt% B is cooled down slowly.
then at around 795 temp it starts solidifying with liquid and phase..
then at around 715 temp completely solidified and only phase will be present.
and at around 650 temp phase converted to solid having both phase and AB2.. it continues till 600 temp..
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