1. Chemical Equations Classifying, Predicting, Balancing

2. To Write an Equation Given: reactants  ? What to do: - Classify the reaction as one of 5 types - Based on how the reaction works, write what products will form - Balance the equation with coefficients

3. Classifying Equations Synthesis A + B  AB elem + elem  compound Examples (unbalanced): Na + O 2  Na 2 O Mg + N 2  Mg 3 N 2 K + P  K 3 P

4. Classifying Equations Decomposition AB  A + B compound  elem + elem There are also other types of specific decomposition reactions carbonates: MCO 3  MO + CO 2 chlorates: MClO 3  MCl + O 2 Examples (unbalanced): NaCl  Na + Cl 2 Na 2 CO 3  Na 2 O + CO 2 Fe 2 O 3  Fe + O 2 KClO 3  KCl + O 2 K 2 S  K + S

5. Classifying Equations Single Replacement A + BC  AC + B A + BC  BA + C elem + cmpd  cmpd + elem Examples (unbalanced): Ca + HCl  CaCl 2 + H 2 NaCl + F 2  NaF + Cl 2 Sr(NO 3 ) 2 + Li  LiNO 3 + Sr

6. Classifying Equations Double Replacement AB + CD  AD + CB cmpd + cmpd  cmpd + cmpd Examples (unbalanced): HCl + NaOH  NaCl + HOH AgNO 3 + CaCl 2  AgCl + Ca(NO 3 ) 2 Li 3 PO 4 + KNO 3  LiNO 3 + K 3 PO 4

7. Classifying Equations Combustion of a hydrocarbon C_H_ + O 2  CO 2 + H 2 O hydrocarbon + oxygen  carbon dioxide + water Examples (unbalanced) C 3 H 8 + O 2  CO 2 + H 2 O C 4 H 10 + O 2  CO 2 + H 2 O C 6 H 12 O 6 + O 2  CO 2 + H 2 O

8. Classifying Practice, Part 1 Classify the following reactions: Na + RbCl  NaCl + Rb CH 4 + 2O 2  CO 2 + H 2 O H 2 SO 4 + 2NaOH  2HOH + Na 2 SO 4 NaCl + AgNO 3  AgCl + NaNO 3 2NaCl  2Na + Cl 2 F 2 + 2LiCl  2LiF + Cl 2 AlCl 3 + KOH  Al(OH) 3 + KCl Cl 2 + 2NaI  2NaCl + I 2 2Sn + O 2  2SnO 2HCl  H 2 + Cl 2 2C 3 H 6 + 9O 2  6CO 2 + 6H 2 O

9. Classifying Practice, Part 2 Classify the following reactions: Cl 2 + LiBr  NaCl + Ag 2 SO 4  C 2 H 4 + O 2  Na + RbBr  KCl  Ba + N 2  C 2 H 6 + O 2  AlF 3 + KOH  HCl + NaOH  Cl 2 + K I  Fe + O 2  HF 

10. Predicting Products Based heavily in being able to write formulas. – element names = symbols from periodic table “silver” = Ag; “carbon” = C; “aluminum” = Al 7 diatomic elements: “hydrogen” = H 2 ; “nitrogen” = N 2 ; “oxygen” = O 2 ; “fluorine” = F 2 ; “chlorine” = Cl 2 ; “bromine” = Br 2 ; “iodine” = I 2 – ionic compounds: use charges to determine formula “sodium oxide” = Na +1 and O -2 = Na 2 O “barium nitrate” = Ba +2 and NO 3 -1 = Ba(NO 3 ) 2

11. Predicting Products Must classify FIRST to know how reaction works. Use rules for writing compounds to figure out formulas for products Ca + O 2  KClO 3  MgSO 4 + Li  NaOH + HCl  C 3 H 8 + O 2 

12. Predicting Practice Classify the following reactions: Cl 2 + LiBr  NaCl + Ag 2 SO 4  C 2 H 4 + O 2  Na + RbBr  KCl  Ba + N 2  C 2 H 6 + O 2  AlF 3 + KOH  HCl + NaOH  Cl 2 + K I  Fe + O 2  HF 

13. Balancing Equations According to the LAW OF CONSERVATION OF MASS: – # of atoms on each side of a reaction must be the same (conserved) ___ Ca(NO 3 ) 2 + ___ NaCl  ___ NaNO 3 + ___ CaCl 2

14. Wrap-Up To write a chemical equation: 1.Classify the equation according to the reactants 2.Predict what the products will be. Write their formulas according to rules of nomenclature (if in doubt, look for charges!) 3.Balance the entire equation with coefficients