Question

Which of the following is correct for a solution showing positive deviation?
Here,
$\Delta H_{mix}\text{is the enthalpy of mixing.}$
$\Delta G_{mix}\text{is the gibbs free energy of mixing.}$

• A. $\Delta H_{mix}>0,\Delta G_{mix}>0$
• B. $\Delta H_{mix}>0,\Delta G_{mix}<0$
• C. $\Delta H_{mix}<0,\Delta G_{mix}>0$
• D. $\Delta H_{mix}<0,\Delta G_{mix}<0$

Answer 1

The correct option is B $\Delta H_{mix}>0,\Delta G_{mix}<0$

Positive deviation:
Solvent-solute interaction is less than the solvent-solvent and the solute-solute interactions

For positive deviation:

$\Delta H_{mix}>0$
$\Delta S_{mix}>0$
$\Delta G_{mix}<0$
Examples: Ethanol and Acetone, $C{S}_2$ and acetone