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Certain substances that are called electrolytes produce ions when they
dissolve in solution. Because these ions are free to move in solution,
the solution conducts electricity. Ions can be produced in solution in
either of two ways. Electrolytes can be
either ionic compounds
(i.e. sodium hydroxide, potassium nitrate) that
dissolve in water, giving solutions of ions, or they may be covalent
compounds that react with water and form ions in solution as a result.
- When an ionic substance such as NaCl dissolves in H2O, the
water then separates the ions present in the NaCl crystal lattice. This
process, known as dissociation, is shown below:
Na+Cl-(s) --> Na+(aq) + Cl-(aq)
- When a polar covalent substance such as HCl dissolves in water, ions are created by the interaction between HCl and H2O molecules. This process, known as ionization is shown below:
HCl(g) + H 2O(l) --> H3O+(aq) + Cl-(aq)
When the boiling and freezing points of solutions of electrolytes are
seen, it's found that they don't follow the simple relationship t=k*m. The boiling points are higher, and the freezing points are lower, than what is expected.
Nonelectrolytes are compounds that don't ionize when they dissolve in
water. Nonelectrolytes are limited to covalent compounds. Many
compounds of carbon such as mathane CH4, benzene
C6H6, ethanol C2H5OH, ether
(C2H5)2O, and formaldehyde
CH2O, are nonelectrolytes. A few inorganic compounds such as
nitrous oxide N2O, phosphine PH3, and
nitrogen(III) chloride NCl3, are nonelectrolytes.