What are the molecular, word, complete ionic, and net ionic equations for the reaction between #"AuBr"_3"# and #"H"_2"CO"_3"#?

This is a double replacement (double displacement) reaction.

The generic equation is #"AB + XY"##rarr##"AY + XB"#, where #"A"# and #"X"# are cations, and #"B"# and #"Y"# are anions. The products of a double replacement reaction must include a precipitate (insoluble solid), water, or gas.

The molecular equation is:

#"2AuBr"_3("aq") + "3H"_2"CO"_3("aq")"##rarr##"Au"_2("CO"_3)_3("s")darr + "6HBr(aq)"#

**The down arrow means that the compound is a solid that precipitated out of solution.

The word equation for this reaction is:

Three moles of aqueous gold bromide plus three moles of aqueous carbonic acid yield one mole of solid gold carbonate and six moles of aqueous hydrobromic acid. Because one of the products is a precipitate (solid), this is a double replacement reaction.

Complete ionic equation

The complete ionic equation includes all of the individual ions and the precipitate (solid). Notice that the coefficents are included so that the ions balance on both sides of the equation.

#"2Au"^(3+)("aq") + "6Br"^(-)("aq") + "6H"^(+)("aq") + "3CO"_3^(2-)("aq")"##rarr##"Au"_2("CO"_3)_3("s") + "6H"^(+)("aq") + "6Br"^(-)("aq")"#

Net ionic equation

The net ionic equation includes only those ions that reacted to form the precipitate, and the precipitate.

#"2Au"^(3+)("aq") + "3CO"_3^(2-)("aq")"##rarr## "Au"_2("CO"_3)_3("s")"#