Question

Which of the following is true for a non-ideal solution showing negative deviation from Raoult’s law?

• A. ${\Delta }_{\text{mix}}H>0$
• B. ${\Delta }_{\text{mix}}H<0$
• C. ${\Delta }_{\text{mix}}V>0$
• D. ${\Delta }_{\text{mix}}V=0$

Answer 1

The correct option is B ${\Delta }_{\text{mix}}H<0$

The solution shows a negative deviation from Raoult's law, when molecular interaction between solute-solvent is stronger than solvent-solvent and solute-solute molecules $A-B>A-AorB-B$
For a non-ideal solution showing negative deviation ${\Delta }_{\text{mix}}H<0$ because more is heat is evolved when new interactions are formed.