Question

Write the balanced net ionic equation for the reaction of aqueous sodium sulfide with aqueous lead(II) nitrate. Include phases.

Answer 1

The question requires us to write the balanced net ionic equation for the reaction between aqueous sodium sulfide (Na2S) and aqueous lead(II) nitrate (Pb(NO3)2).

The reaction between Na2S and Pb(NO3)2 leads to the formation of aqueous sodium nitrate (NaNO3) and the solide lead(II) sulfide (PbS). We can write the molecular equation for this reaction as:

`Na_2S_((aq))+Pb(NO_3)_(2(aq))\to2NaNO_(3(aq))+PbS_((s))`

(note that the molecular equation above is already balanced)

We can also write the ionic equation for this reaction, considering the ions from only the compounds that are in aqueous form:

`2Na^+_((aq))+S^(2-)_((aq))+Pb^(2+)_((aq))+2NO^-_(3(aq))\to2Na^+_((aq))+2NO^-_(3(aq))+PbS_((s))`

We can see in the ionic equation that both sodium and nitrate ions appeared unchanged on both sides of the equation, thus they can be eliminated from the equation (because they don't actually participate in the reaction - these are the spectator ions). Removing these ions, we'll have:

`S^(2-)_((aq))+Pb^(2+)_((aq))\to PbS_((s))`

The equation above, involving only the ions S2- and Pb2+, corresponds to the net ionic equation, where only the elements, compounds, and ions that are directly involved in the chemical reaction are shown.