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Solve! Which is correct w.r.t non-ideal solution?

Which is correct w.r.t non-ideal solution?

  • Option 1)

    Solution obeys Raoult's Law over the entire range of concentration. 

  • Option 2)

    The vapour pressure is always higher than that predicted by Raoult's Law

  • Option 3)

    The cause for the deviations lie in the nature of interactions at the molecular level

  • Option 4)

    All of these

 
Answers (1)
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V Vakul

As learnt in

Condition for positive deviation -

When A - A interactions and B - B  interactions  are  stronger than A - B interactions.

e.g. Ethanol + water

- wherein

\Delta H_{mix}> 0

\Delta V_{mix}> 0

(V_{f}>V_{A}+V_{B} )

\Delta H - Change\: in\: enthalpy

\Delta V - Change\: in\: volume

 

 

Condition for negative deviation -

When A - A interactions and B - B  interactions  are  weaker than A - B interactions.

e.g. Acetone + Chloroform

- wherein

\Delta H_{mix}< 0

\Delta V_{mix}< 0

(V_{f}< V_{A}+V_{B} )

\Delta H - Change\: in\: enthalpy

\Delta V - Change\: in\: volume

 

Any solution that shows deviation from Raoult's law is called a non-ideal solution. Direction can be both positive and negative.
Positive deviation is observed when A-A interactions are stronger than A-B interactions.
Negative deviation is observed when A-A and B-B interactions are weaker than A-B interactions. 

 

 

 


Option 1)

Solution obeys Raoult's Law over the entire range of concentration. 

This solution is incorrect

Option 2)

The vapour pressure is always higher than that predicted by Raoult's Law

This solution is incorrect

Option 3)

The cause for the deviations lie in the nature of interactions at the molecular level

This solution is correct

Option 4)

All of these

This solution is incorrect

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