1. Ionic Equations & Reactions

2. Equations
Molecular equations – show the complete chemical formulas. Does not indicate ionic character
Complete ionic equation – shows all ions. Actually how the particles exist in the solution

3. Steps for Writing Ionic Equations
Write the balances molecular equation (balanced chemical equation)
Break every thing down into its ions EXCEPT the solid, gas, water, or weak electrolyte (complete ionic equation)
Cross out everything that is the same on both sides (spectator ions)
Write what is left (net ionic equation)

4. Rules
When writing ionic equations, you must keep together the solid, gas, water, or weak electrolyte
Spectator ions – ions that appear on both sides of the equation. They have very little to do with the chemical reaction

5. Example
Write the balanced chemical equation, the complete ionic equation, and the net ionic equation for the reaction between lead (II) nitrate and potassium iodide

6. Example Write the balanced chemical equation
Pb(NO3)2 + 2 KI  PbI2 + 2 KNO3
You MUST identify the solid, gas, or water
Pb(NO3)2 + 2 KI  PbI2 (s) + 2 KNO3
Balanced chemical equation

7. Example
Now break every thing except the solid, gas, or water into its ions
Remember ions are things with charges
Everything will be broken down into one positive charge and one negative charge

8. Example Pb(NO3)2 + 2 KI  PbI2 (s) + 2 KNO3 Complete ionic Equation

9. Example
Now cross out everything that is the same on both sides (spectator ions)
Pb+2 + 2NO K I -1  PbI2 (s) + 2K+1 + 2NO3-1
Now write what is left
Pb I -1  PbI2 (s)
Net ionic equation

10. Another Example
Write the balanced chemical equation, complete ionic equation, and net ionic equation for the reaction between calcium chloride and sodium acetate

11. Another Example Balanced chemical equation
CaCl2 + Na2CO3  CaCO3 (s) + 2NaCl
Complete ionic equation
Ca+2 + 2Cl Na +1 + CO3 -2  CaCO3 (s) + 2Na Cl -1
Net Ionic Equation
Ca+2 + CO3 -2  CaCO3 (s)

12. What if water is formed?
Write the balanced chemical equation, complete ionic equation, and net ionic equation for the reaction between Calcium hydroxide and nitric acid

13. Example with water 2(OH) -1 + 2H+1  2 HOH Balanced chemical equation
Ca(OH)2 + 2 HNO3  Ca(NO3)2 + 2 HOH
Complete ionic equation
Ca+2 + 2(OH) H+1 + 2NO3 -1  Ca+2 + 2NO HOH
Net Ionic Equation
2(OH) H+1  2 HOH

14. 5 Major Types of Reactions
We will be discussing 5 major types of reactions
Synthesis
Decomposition
Single Replacement
Double Replacement
Combustion
You need to know these reactions!
Note cards are an extremely effective way to remember them

15. Synthesis # 1
Metal oxide + nonmetal oxide  metal oxyanion (NO ions – No Redox)
No Redox simply means that the oxidation numbers of the elements stays the same

16. Synthesis # 1 Example
Sulfur dioxide gas is passed over solid calcium oxide
SO2 + CaO 
We know that we have to get a metal oxyanion.
So we either get CaSO4 or CaSO3
We need to check the oxidation states on sulfur to see which one is the same.

17. Synthesis # 1 Example In SO2, the oxidation number of O is -2
So the oxidation number of S must be +4
Our product choices are CaSO3 or CaSO4
In CaSO3…S has an oxidation # of +4
In CaSO4…S has an oxidation # of +6
Therefore the product must be CaSO3
SO2 + CaO  CaSO3

18. Synthesis # 2 Metal oxide + water  strong base (IONS)
Strong acids & bases ionize completely in water & are therefore electrolytes.
They will be written as ions
Strong bases…Group !a or 2A hydroxides
There are 7 strong acids…
HCl, HBr, HI, HNO3, HClO3, HClO4, H2SO4
You MUST know these!

19. Synthesis # 2 Example Solid sodium oxide is added to water
Na2O + H2O 
Na2O + H2O  NaOH
Na2O + H2O  2NaOH
Na2O stays together because it is solid
H2O stays together because it is water
NaOH is separated because it is a strong base
Na2O + H2O  2Na+ + OH-

20. Synthesis # 3
Non metal oxide + water  oxyacid (weak molecules…strong ions…No Redox)
Sulfur dioxide gas is placed in water
SO2 + H2O 
We are going to get an oxyacid…so we either have H2SO3 or H2SO4
The S needs to have the same oxidation number

21. Synthesis # 3 Example
In SO2, O has an oxidation # of -2…so S has an oxidation # of +4
In H2SO3…S has an oxidation # of +4
In H2SO4…S has an oxidation # of +6
Therefore we will get In H2SO3
SO2 + H2O  H2SO3
Since H2SO3 is a weak acid…we will keep it together

22. Synthesis # 4 Metal + nonmetal  salt (NO ions)
A salt is just an ionic compound ( a positive charge & a negative charge)
Magnesium metal is combusted in nitrogen gas
Mg + N2 
Mg + N2  Mg3N2
3Mg + N2  Mg3N2

23. Decomposition # 1
Metal oxyanion  metal oxide + nonmetal oxide (No Redox – NO ions)
A solid sample of calcium sulfate is heated
CaSO4 
CaSO4  CaO + SO3

24. Decomposition # 2 Base  metal oxide + water (No Redox – NO ions)
Calcium hydroxide is decomposed
Ca(OH)2 
Ca(OH)2  CaO + H2O

25. Single Replacement # 1
Metal + ionic solution  Metal ion + metal (will have ions)
Must look at activity series!
Aluminum metal is added to a solution of copper (II) chloride
Al + CuCl2 
Al + CuCl2  AlCl3 + Cu
2Al + 3CuCl2  2AlCl3 + 3Cu
2Al + 3Cu +2  2Al Cu

26. Single Replacement # 2
Active metal (Group 1A, Ba, Ca, Sr) + water  H2 + strong base (IONS)
Sodium is placed in water
Na + H2O 
Na + H2O  H2 + NaOH
2Na + 2H2O  H2 + 2NaOH
2Na + 2H2O  H2 + 2Na+ + 2OH-

27. Single Replacement # 3
Halogen + metal halide  new metal halide + halogen (REDOX…will have ions)
Chlorine gas is bubbled into a solution of sodium bromide
Cl2 + NaBr 
Cl2 + NaBr  NaCl + Br2
Cl2 + 2NaBr  2NaCl + Br2
Cl2 + 2Br-  2Cl- + Br2

28. Double Replacement # 1
Precipitate (must know solubility rules)…the precipitate will stay together
A saturated solution of barium hydroxide is mixed with a solution of iron (III) sulfate
Ba(OH)2 + Fe2(SO4)3 
Ba(OH)2 + Fe2(SO4)3  Fe(OH)3 + BaSO4(s)
3Ba(OH)2 + Fe2(SO4)3  2Fe(OH)3 + 3BaSO4(s)
3Ba+2 + 3SO4-2  3BaSO4(s)

29. Double Replacement # 2
Formation of a gas (acid + sulfide, carbonate, or bicarbonate)
Hydrobromic acid is added to a solution of potassium bicarbonate
HBr + KHCO3 
HBr + KHCO3  H2CO3 + KBr
H2CO3 ALWAYS breaks down into CO2 + H2O
HBr + KHCO3 CO2 + H2O + KBr
H+ + HCO3- CO2 + H2O

30. Double Replacement # 3 Metal hydride + water  H2 + strong base (IONS)
Sodium hydride is placed into water
NaH + H2O 
NaH + H2O  H2 + NaOH
NaH + H2O  H2 + Na+ + OH-

31. Combustion Hydrocarbon + O2 CO2+ H2O (No ions) Combustion of methane
CH4 + O2 CO2+ H2O
CH4 + 2O2 CO2+ 2H2O