what is the net ionic equation for gold and hydrobromic acid?

Expert Answers
jerichorayel eNotes educator| Certified Educator

The chemical equation for the reaction of gold and hydrobromic acid can be expressed as:

`Au _(s) + HBr _(aq) -> AuBr_3 _(aq) + H_2 _(g) `

Balancing the reaction, we can have:

`2 Au _(s) + 6 HBr _(aq) -> 2 AuBr_3 _(aq) + 3 H_2 _(g) `

The next thing to do is to show the ionic forms of the species that are ions in the solution. This is also the complete ionic equation of the reaction of Au and HBr. 

`2 Au _(s) + 6 H^(+) _(aq) + 6 Br^(-)_(aq)-> 2 Au ^(3+) + 6 Br^(-)_(aq)+ 3 H_2 _(g) `

To get the net ionic equation, you will remove (in other case, subtract) the spectator ions. These ions are those that are present in the reactants and product side. Since both sides of the reaction contain 6 moles of Br-, it can be removed. 

`2 Au _(s) + 6 H^(+)_(aq)-> 2 Au ^(3+) _(aq) + 3 H_2 _(g) `

Take note that Au and H have different states in the reactant and product side. 

ayl0124 | Student

Find a very form of your chemical reaction:

`Au + HBr -> AuBr_3 + H_2`

Balance it:

`2Au + 6 HBr -> 2AuBr_3 + 3 H_2`

You should have equal amounts of each element on either side of the reaction. 

Split the ionic bonds:

`2Au + 6 H^+ + 6 Br^(-) -> 2Au^(3+) + 6 Br^(-) + 3H_2`

In a net ionic equation, you can cancel out any ions or molecules that are on both sides of the equation (spectator ions). In the reactants, there are 6 bromide ions. Likewise, in the products, there are 6 bromide ions. The bromide ions cancel each other out.

`2Au + 6H^+ -> 2Au^(3+) + 3H_2`

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