BARC-1: In a Eutectic Phase Diagram, Lever Rule can be applied just above Eutectic Temp or Just below. But not at the Eutectic Temp. What is the Reason?

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This answer was edited.The answer is quite simple!! If you remember the derivation of Level Rule, it is derived for a Two-Phase Equilibrium. At the Eutectic Point, there is a three-phase Equilibrium and hence it cannot be applied !! :) :) We will post the Questions at the start of the Day and answers at the End of the DayRead more

The answer is quite simple!!

If you remember the derivation of

Level Rule, it is derived for aTwo-Phase Equilibrium. At the Eutectic Point, there is a three-phase Equilibrium and hence it cannot be applied !! 🙂 🙂We will post the Questions at the start of the Day and answers at the End of the Day !! Good Luck to all

See lessThis answer was edited.Because lever rule is used to find the composition of two phases that are in equilibrium. But at the eutectic point, the phases present are in dynamic equilibrium. To apply a mass balance equation there were require one more parameter i.e rate of heat. Without knowing how much heat is taken out or hRead more

Because lever rule is used to find the composition of two phases that are in equilibrium. But at the eutectic point, the phases present are in dynamic equilibrium. To apply a mass balance equation there were require one more parameter i.e rate of heat. Without knowing how much heat is taken out or how much heat is given to the system we can’t apply any mass balance equation. So we’re not able to apply lever rule at the eutectic point.

Whereas we can apply above and below eutectic temperature because equilibrium present there is not dynamic.

See lessWhere you know about dynamic equilibrium.

Lever rule can be applied on two phase region

Lever rule can be applied on two phase region

See less👍

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See lessThis answer was edited.The lever rule is a rule used to determine the mole fraction or the mass fraction of each phase of a binary equilibrium phase diagram. It can be used to determine the fraction of liquid and solid phases for a given binary composition and temperature that is between the liquidus and solidus line. ThRead more

lever ruleis a rule used to determine the mole fraction or the mass fraction of each phase of a binary equilibrium phase diagram.^{l}is the mass fraction of the whole sample in the liquid phase:ConclusionLever Rule can’t applied on Eutectic Point due to three phase, it describes two phase equilibrium.Because , the eutectic point is an invariant point in which the possibility of distinguishing a variable or degrees of freedom is zero

Because , the eutectic point is an invariant point in which the possibility of distinguishing a variable or degrees of freedom is zero

See lessLever rule is used to find out the weight percentages in an alloy at particular composition of an alloy.

Lever rule is used to find out the weight percentages in an alloy at particular composition of an alloy.

See lessIn the thermodynamic view. The interaction parameter (omega) come into picture.. 1. At the eutectic line(below or above) the interaction parameter close to zero but not zero. So the phases are miscible.(nither repulsive nor attractive to each other) So this is what causes dynamic equilibrium.. As wRead more

In the thermodynamic view.

The interaction parameter (omega) come into picture..

1. At the eutectic line(below or above) the interaction parameter close to zero but not zero.

So the phases are miscible.(nither repulsive nor attractive to each other)

So this is what causes dynamic equilibrium..

As we going far from line this interaction parameter changes.. So we can not calculate.

I can't understand. Please elaborate more

I can’t understand. Please elaborate more

See lessBecause eutectic point is an invariant point where degree of freedom is zero so lever rule is applied above or below eutectic point.

Because eutectic point is an invariant point where degree of freedom is zero so lever rule is applied above or below eutectic point.

See lessAt eutectic point all three phases coexist with each other.

At eutectic point all three phases coexist with each other.

See less