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Writing Reactions  (Molecular, Ionic and Net Ionic) Equations

 

 

This may seem overwhelming, but I broke it down step by step for you.

Read the rules, watch the video, then practice it a few times and it is really not that bad.

 

Before you do anything, you are going to need 4 lines to do this.

          **Top line is for the reaction in word form

          **2nd is the Molecular formula equation

          **3rd is the Ionic Equation

          **4th is the Net Ionic Equation

 

If you are given the formulas of the reactants (Click here if you have NAMES)

(1 page printable PDF of these steps)

 K2SO4(aq) + BaCl(aq)

 

The Steps

1. On line 2...Write the formulas of each reactant and place an ==> after them.

2. On line 1...Write the names of each of the reactants.

3. On line 1...Write these and the names of products by switching last names of the reactants

                                    (Once you get some practice this step can be skipped)

4. Check solubility to determine if there is a reaction. If there is no reaction...STOP!!!!!

                                    (You do not want to do all this work if there is no reaction.)

                                    (Link<==Determining of there is a reaction)

5. On line 3...If there is a solid, liquid or gas formed,  write each of the 4 ions with the correct charges.

                                   (Separate each with a "+" and place an "=>" after the 4th ion.)

6. On Line 2...Now write the correct formulas of the products. Remember the ions switch partners.

                                    (the ratios may be different, pay attention to the charges.)

                                    (**How to write formulas review => LINK)

7. On line 2... Using the solubility rules, write the phase of each compound as a (subscript) after the formula.

                                   (soluble=(aq), insoluble = (s), watch for the 5 exceptions=>LINK to Sol. Rules)

7. On line 3 and 4...Any solid liquid or gas can copied as in onto the lower lines.

                                   (just write them as they appear on line 2, keep them on the right side of the arrow.)

9. On line 3... If a product is soluble (aq) in line 2, write the ions that make it up under it with "+" between them.

                                   (just copy those ions from the left side of the arrow and put them on the right.)

                                   (add (aq) to all ions...tedious step)

10. On line 2... Now you can balance the Molecular reaction

                                   (keep yourself from balancing the reaction until the 2 reactions are finished.)

11. On line 3...You have to add coefficients to the ions and the compounds using the reaction form line 2.

                                   (take the subscript for the ion (if it has one) and multiply it by the coefficient.)

                                   (for the compound, just copy the coefficient from the previous reaction.)

12. On line 4... Ignore all spectator ions on line 3,  and place the remaining ions on line 4 with coefficients.

                                   (Spectator ions appear the same on both sides of the reaction.)

                                   (They don't actually participate in the reaction.)

                                   (If you did this correctly the ions should for the product)

13. On line 4...Reduce the confidents to the lowest whole number ratio

PRACTICE PROBLEMS-

 Write balanced formula unit, total ionic and net ionic equations for the following reactions. Assume all reactions occur in water or in contact with water.    

1. AgNO3 (aq) + RbCl(aq)

Overall Equation:
AgNO3 (aq) + RbCl(aq) --> AgCl(s) + RbNO3 (aq)

Total Ionic Equation:
Ag+ (aq) + NO3- (aq) + Rb+(aq) + Cl-(aq) -> AgCl(s) + Rb+(aq) + NO3- (aq)
Net Ionic Equation:
Ag+ (aq) + Cl-(aq) -> AgCl(s)
 

2. Hg2(NO3)2 (aq) +  HCl (aq)

Overall Equation:
Hg2(NO3)2 (aq) + 2 HCl (aq) --> Hg2Cl2 (s) + 2 HNO3 (aq)
Total Ionic Equation:
Hg22+(aq) + 2 NO3- (aq) + 2 H+(aq) + 2 Cl- (aq) --> Hg2Cl2 (s) + 2 H+ (aq) + 2 NO3-(aq)
Net Ionic Equation:
Hg2+(aq) + 2 Cl- (aq) --> Hg2Cl2 (s)
 

3. CaCl2 (aq) + Na2CO3 (aq)

Overall Equation:
CaCl2 (aq) + Na2CO3 (aq) -> 2 NaCl(aq) + CaCO3 (s)

Total Ionic Equation:
Ca2+(aq)+ 2 Cl- (aq) + 2 Na+ (aq)+ CO32- (aq) -> 2 Na+(aq) + 2 Cl-(aq) + CaCO3 (s)
Net Ionic Equation:
Ca2+(aq) + CO32- (aq) -> CaCO3 (s)

 

4. Mg(NO3)2 (aq) + CaCl2 (aq)

Overall Equation:
Mg(NO3)2 (aq) + CaCl2 (aq) -> Ca(NO3)2 (aq) + MgCl2 (aq)

Total Ionic Equation:
Mg2+ (aq) + 2 NO3- (aq) + Ca2+ (aq) + 2 Cl- (aq) --> Ca 2+(aq) + 2 NO3- (aq) + Mg2+(aq) + 2 Cl- (aq)
Net Ionic Equation:
No Reaction

 

5. K2SO4 (aq) + BaCl2 (aq)

Overall Equation:
K2SO4 (aq) + BaCl2 (aq) --> BaSO4 (s) + 2 KCl (aq)

Total Ionic Equation:
2 K+ (aq)+ SO42- (aq) + Ba2+ (aq) + 2 Cl- (aq) --> BaSO4 (s) + 2 K+(aq)+ 2 Cl- (aq)
Net Ionic Equation:
SO42- (aq) + Ba2+ (aq) -> BaSO4 (s)

More problems- AP Chemistry

1) HC2H3O2  +  NaOH 

 

ANSWER

1)     Formula Unit:       HC2H3O2  +  NaOH    NaC2H3O2  + H2O
 Total Ionic:        HC2H3O2     + Na+1  + OH-1    Na+1  +  C2H3O2-1  + H2O

Weak acid

Net Ionic:         HC2H3O2    + OH-1     C2H3O2-1  + H2O

2) Ca(OH)2  +  H2S 

 ANSWER

2)     Formula Unit:      Ca(OH)2  +  H2S    CaS  +  2 H2O
 Total Ionic:        Ca+2  +  2OH-1  +  2H +1  +  S-2      Ca+2  +  S-2  +  2 H2O
Net Ionic:          2OH-1  +  2H +1      2 H2O

 OH-1  +  H +1      H2O

   3)Ba(NO3)2  + K2CO3

 ANSWER

3)     Formula Unit:      Ba(NO3)2  + K2CO3    BaCO3  +  2KNO3
 Total Ionic:        Ba+2  +  2NO3-1   +  2K +1  +  CO3-2    BaCO3  Insoluble   +  2K+1 +  2NO3-1
Net Ionic:         Ba+2  +  CO3-2    BaCO3   Insoluble   

  4) Pb(OH)2  + H2CO3 

 ANSWER

4)     Formula Unit:      Pb(OH)2  + H2CO3    PbCO3  +  2H2O
 Total Ionic:        Pb(OH)2  +        H2CO3            PbCO3  +     2H2O

 Insoluble       Weak Acid            Insoluble        liquid 

Net Ionic:         Pb(OH)2  + H2CO3    PbCO3  +  2H2O

 

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