Question

1.HCL is a molecular compound yet is a strong electrolyte. What obviously must happen when HCL is dissolved in water? What specific species are responsible for HCL being a strong electrolyte?

2. A 1M solution of CaCk2is an even stronger electrolyte than 1 M NaCl. Why?

3

Answer 1

(1) HCl is a molecular compound where a weak vanderwaals attractive forces can act among the molecules.

But when HCl is added to water it undergoes ionisation where obtained ions H+ and Cl - are stabilised by solvent water molecules called hydration by losing much amount of energy. Thus HCl is easily ionised to more stable state than that of HCl

(2) Though the lattice enthalpy of CaCl₂ is greater than NaCl, The dissolution enthalpy of CaCl₂ is greater than NaCl. Because CaCl₂ on dissociation gives a dipositive ion and two uni negative chloride ions which are stabilised by hydration process by giving energy. Where as in NaCl on dissociation one one positive and one negative ion are produced and stabilised by hydration energy. Here the Hydration energy of CaCl₂ is Greater than NaCl and thus CaCl₂ is stronger electrolyte than NaCl.