Hi,
The enthalpy of crystallization of KCl (Potassium Chloride) is + 715 kJ / mol. The enthalpies of hydration for Potassium and Chloride are -322 and -363 kJ/mol respectively. So, enthalpy of solution of KCl Δ Hsol=Δ H lattice - Δ H hydration.

ΔH sol=715 kJ/mol -685 kJ/mol= 30 kJ/mol.

But if you see table of enthalpy of solution, it is -17.22 kJ/mol for KCl(s). Obviously, our experiment value 30 kJ/mol indicates dissolving KCl into water is endothermic reaction. Should the temperature increase or decrease when  KCl dissolves?

My answer is temperature  increase when KCl dissolves.

    What types of interaction are present when CaCl₂ dissolves in ethanol?
    My answer: Ion-dipole

    What is the major type of interaction when toluene dissolves in benzene?
   My answer: At present, I  don't know. I have to find out through studying reference books.

    Which ion has a larger absolute value of enthalpy of hydration, Na⁺ or Ca²⁺?
     My answer: Ca²⁺

    Which ion is larger, Na⁺ or Cl⁻?
   My answer:Cl⁻

    When KNO₃ is dissolving in water, will the temperature decrease or increase?
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Quote from: Dhamnekar Winod on November 01, 2020, 01:17:26 AM


But if you see table of enthalpy of solution, it is -17.22 kJ/mol for KCl(s). Obviously, our experiment value 30 kJ/mol indicates dissolving KCl into water is endothermic reaction. Should the temperature increase or decrease when  KCl dissolves?

My answer is temperature  increase when KCl dissolves.

   

KCl dissolution is endothermic in nature. Experimentally also you are gettng +30kJ of energy,a positive delta H is positive means endothermic process and it will decrease the temperature of water.

QuoteWhat is the major type of interaction when toluene dissolves in benzene?
   My answer: At present, I  don't know. I have to find out through studying reference books.

Benzene and toluene are non-polar compounds (Hydrocarbons) .In Non - polar compounds attractive forces are London dispersion forces which depend on molar mass and size.

QuoteWhich ion has a larger absolute value of enthalpy of hydration, Na⁺ or Ca²⁺?
     My answer: Ca²⁺

Hydration enthalpy is the energy released when attractive forces are formed between solute and solvent.
These forces depend on
1) Charge - more charge, more attraction
2) Size -small size more attraction