Electrolytes

• An electrolyte is a substance that allows the flow of an electric current when in an aqueous solution.

• A nonelectrolyte is a substance that does not allow the flow of an electric current when in an aqueous solution.

In the following diagram, the aqueous solution of sodium chloride |(\text{NaCl}),| a salt, contains |\text{Na}^+| and |\text{Cl}^-| ions. This solution conducts an electric current, as evidenced by the light emitted by the light bulb. Sodium chloride |(\text{NaCl})| is an electrolyte.

Glucose |(\text{C}_6\text{H}{_{12}}\text{O}_6),| oxygen |(\text{O}_2)| and carbon dioxide  |(\text{CO}_2)| are examples of nonelectrolytes.

In the following diagram, the aqueous solution of glucose |(\text{C}_6\text{H}{_{12}}\text{O}_6)| does not contain ions. This solution does not conduct an electric current, as evidenced by the light bulb that does not emit light. Glucose |(\text{C}_6\text{H}{_{12}}\text{O}_6)| is a nonelectrolyte.

An acid is an electrolyte that releases |\text{H}^+| ions in an aqueous solution.

The chemical formula of an acid usually begins with a hydrogen symbol |(\color{red}{\text{H}})| followed by a non-metal.

• Hydrofluoric acid |(\color{red}{\text{H}}\text{F})|

• Hydrochloric acid |(\color{red}{\text{H}}\text{Cl})|

• Hydriodic acid |(\color{red}{\text{H}}\text{I})|

The fluorine |(\text{F}),| chlorine |(\text{Cl})| and iodine |(\text{I})| are non-metals.

• Nitric acid |(\color{red}{\text{H}}\text{NO}_3)|

• Sulfuric acid |(\color{red}{\text{H}_2}\text{SO}_4)|

The chemical formula of acetic acid |(\text{CH}{_3}\text{COO}\color{red}{\text{H}})| ends with the hydrogen symbol |(\color{red}{\text{H}}).|

• |\text{HF}_{\text{(g)}}\rightarrow\text{H}^{+}{_{\text{(aq)}}}+\text{F}^{-}{_{\text{(aq)}}}|

• |\text{H}_2\text{SO}_{4}{_{\text{(l)}}}\rightarrow2\ \text{H}^{+}{_{\text{(aq)}}}\ +\ \text{SO}_{4}{^{2-}}{_\text{(aq)}}|

• |\text{CH}_{3}\text{COOH}_{\text{(l)}}\rightarrow\text{H}^{+}{_{\text{(aq)}}}+\text{CH}_{3}\text{COO}^{-}{_{\text{(aq)}}}|

A base is an electrolyte that allows the release of |\text{OH}^-| ions in an aqueous solution.

The chemical formula of a base usually begins with a metal followed by a hydroxyl group |(\color{blue}{\text{OH}}).|

• Lithium hydroxide |(\text{Li}\color{blue}{\text{OH}})|

• Sodium hydroxide |(\text{Na}\color{blue}{\text{OH}})|

• Calcium hydroxide |(\text{Ca(}\color{blue}{\text{OH}})_2)|

Lithium |(\text{Li}),| sodium |(\text{Na})| and calcium |(\text{Ca})| are metals.

The chemical formula of ammonia |(\text{NH}_3)| does not end with |\text{OH}.| Ammonia reacts with water |(\text{H}{_2}\text{O})| according to the following equation:
||\text{NH}_{3}{_{\text{(g)}}}+\text{H}_2\text{O}{_\text{(l)}}\rightarrow\text{NH}{_4}^{+}{_{\text{(aq)}}}+\text{OH}^{-}{_{\text{(aq)}}}||

The reaction between |\text{NH}_3| and water releases |\text{OH}^-| ions, which means that |\text{NH}_3| is a base.

Ammonium hydroxide |(\text{NH}{_4}\color{blue}{\text{OH}})| is formed of a group of atoms |\text{NH}{_4}| and a hydroxyl group |\text{OH}.|

The chemical formula of the acetic acid |(\text{CH}{_3}\text{COOH})| ends with |\text{OH},| but it is not a base. Acetic acid dissociates in water according to the following equation: ||\text{CH}_{3}\text{COOH}_{\text{(l)}}\rightarrow\text{H}^{+}{_{\text{(aq)}}}+\text{CH}_{3}\text{COO}^{-}{_{\text{(aq)}}}||

The dissociation releases |\text{H}^+| ions, which means that |\text{CH}{_3}\text{COOH}| is an acid.

• |\text{NaOH}_{\text{(s)}}\rightarrow\text{Na}^{+}{_{\text{(aq)}}}+\text{OH}^{-}{_{\text{(aq)}}}|

• |\text{Mg}\text{(OH)}_{2}{_{\text{(s)}}}\rightarrow\text{Mg}^{2+}{_{\text{(aq)}}}\ +\ 2\ \text{OH}{^{-}}{_\text{(aq)}}|

• |\text{NH}_4\text{OH}{_{\text{(l)}}}\rightarrow\text{NH}{_4}^{+}{_{\text{(aq)}}}\ +\ \text{OH}{^{-}}{_\text{(aq)}}|

A salt is an electrolyte usually made up of a metal and a non-metal.

• Lithium fluoride |(\text{LiF})|

• Sodium chloride |(\text{NaCl})|

• Calcium oxyde |(\text{CaO})|

Lithium |(\text{Li}),| sodium |(\text{Na})| and calcium |(\text{Ca})| are metals.

Fluorine |(\text{F}),| chlorine |(\text{Cl})| and oxygen |(\text{O})| are non-metals.

• Sodium nitrate |(\text{NaNO}_3)| contains sodium |(\text{Na}),| a metal and a group of atoms |\text{NO}{_3}.|

• Ammonium chloride |(\text{NH}{_4}\text{Cl})| contains a group of atoms |\text{NH}_4| and chlorine |(\text{Cl}),| a non-metal.

• Ammonium nitrate |(\text{NH}{_4}\text{NO}{_3})| contains a group of atoms |\text{NH}_4| and another group of atoms |\text{NO}{_3}.|

• |\text{NaCl}_{\text{(s)}}\rightarrow\text{Na}^{+}{_{\text{(aq)}}}+\text{Cl}^{-}{_{\text{(aq)}}}|

• |\text{CaO}_{\text{(s)}}\rightarrow\text{Ca}^{2+}{_{\text{(aq)}}}+\text{O}^{2-}{_{\text{(aq)}}}|

• |\text{NH}{_4}\text{NO}{_3}_{\text{(s)}}\rightarrow\text{NH}{_4}^{+}{_{\text{(aq)}}}+\text{NO}{_3}^{-}{_{\text{(aq)}}}|

• A strong electrolyte is one that dissociates almost completely in water.

• A weak electrolyte is one that partially dissociates in water.

In the following diagram, all the particles of sodium chloride |(\text{NaCl})| dissociate into |(\text{Na}^+)| and |(\text{Cl}^-)| ions. This solution conducts the electric current very well, as evidenced by the bright light emitted by the light bulb. Sodium chloride |(\text{NaCl})| is a strong electrolyte.

In the following diagram, all the particles of silver chloride |(\text{AgCl})| dissociate into |(\text{Ag}^+)| and |(\text{Cl}^-)| ions. This solution conducts the electric current but not well, as evidenced by the dim light emitted by the light bulb. Silver chloride |(\text{AgCl})| is a weak electrolyte.