Balanced Molecular Equation
Write a balanced molecular equation, complete ionic equation, and net ionic equation for the reaction that occurs when a solution of sodium sulfide is mixed with a solution of lead(II) nitrate. Include all phase labels (aq, s, g, l, etc), and identify the spectator ions.
Make sure you have the table of solubility beside you because you're going to need it!
Step 1: Write out two compounds! Make sure each one has the proper charge while naming them!
NaCl(aq) Pb(NO3)2 (aq) In order to find out whether they are a aq, s, g, or l you must know the rules of solubility or be given the table. These two are aq
Step 2: Now write these equation out. These reactions are usually displacement so all you have to do is replace each anion with the
NaCl(aq) + Pb(NO3)2 (aq) --> NaNo3 + PbCl2
Step 3: Look on the sol. table to know their phases
The table says that any compound with Na+ is aqueous while Cl- is insoluble since it has Pb so it is our solid
NaCl(aq) + Pb(NO3)2 (aq) --> NaNo3(aq) + PbCl2(s)
Step 4 : Balance the equation!
2NaCl(aq) + Pb(NO3)2 (aq) --> 2NaNo3(aq) + PbCl2(s)
Step 4: Time to pull apart each element from the compounds except from the solid (since a solid can not be pull apart)
2Na+(aq) + 2Cl-(aq) + Pb+2(aq) + 2NO3-1 (aq) --> 2Na+(aq) 2No3-(aq) + PbCl2(s)
Step 5: Now all atoms that are not a part of the solid, the spectator ions, will be eliminated to form the complete net ionic equation
2Cl-(aq) + Pb+2(aq) --> PbCl2(s)
And there you have it your complete ionic equation!
The balancing of equations in chemistry is very important as this not only gives an idea of the bonding occurring between two elements, but provides an idea of the electrons lost by one element and gained by another element in the reaction. This hints at the possible shape and structure of the new substance formed after the reaction between the two elements. Furthermore, the net ionic equation is important to identify the ions (solid, liquid, gas) which are present in the resultant aqueous solution formed by the reaction between the elements. The formulas of the reacting elements in this equation are stated below.
The formula of Lead (II) nitrate is Pb(NO3)2 and the formula of sodium sulfide is Na2S.
Step #1: Balance the chemical equation
The balanced molecular equation is
Pb(NO3)2 (aq)+ Na2S (aq) >> 2 NaNO3 (aq)+ PbS (s)
Step #2: Separate the balanced equation of the elements into their compounds to determine the phases (states) occurring in the reaction
The ionic equation is
Pb2+ (aq) + 2 NO3-(aq) + 2 Na+ (aq) + S2-(aq) >>
2Na+ (aq) + 2 NO3-(aq) + PbS (s)
Step #3: Form an equation from the net ionic equation with the compounds which are solid, liquid, gas or a weak electrolyte
The net ionic equation is
Pb2+ (aq) + S2- (aq) >> PbS (s)