What happens in solution

 

When ionic compounds dissolve the cations and anions dissociate. The balanced equation is written as follows:

(Often the solvent is written over the reaction arrow)

Notice that we are now indicating the state of the chemical; s = solid, l = liquid, g = gas, aq = aqueous (dissolved in water), and soln = dissolved in some solvent (soln is uncommon).

When covalently bonded compounds dissolve several things can happen. If the molecule is a weak acid, or a weak base it might ionize partially;

If the molecule is a strong acid then the molecule will ionize completely.

Otherwise, a molecular solid will simply dissolve.

When a molecular solid like sucrose (common sugar) dissolves in water the reaction is written as follows:

Notice that when both ionic compounds and acids dissolve ions form. The solutions that form when these materials dissolve can conduct electricity. Electricity is conducted because the ions are free to move through the solution. Since these solutions conduct electricity they are called electrolytes.

Molecular solids, covalently bonded compounds, do not dissociated into ions; thus, solutions of molecular solids do not conduct electricity (excluding acids of course).

 

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