1. Unit 4: Chemical Equations and Stoichiometry Types of Reactions

2. Chemical Equation Reminders When not part of a compound, diatomic elements are written as: H 2 O 2 F 2 Br 2 I 2 N 2 Cl 2 Charges in a compound formula MUST cancel out to zero When balancing the overall equation, you can only change the COEFFICIENTS

3. Synthesis/Combination Reactions In a synthesis reaction, two or more substances combine to form a new compound. A + B → AB How do you tell? More reactants than products

4. Predicting the Products of Synthesis Reactions Na + Cl 2  Na + Cl 2  NaCl 2Na + Cl 2  2NaCl Al + S  Al + S  Al 2 S 3 2Al + 3S  Al 2 S 3

5. Decomposition Reaction In a decomposition reaction a single compound is broken down to form two or more smaller compounds. AB → A + B How do you tell? More products than reactants

6. Predicting the Products of Decomposition Reactions HgO  2HgO  2Hg + O 2 NaCl  2NaCl  2Na + Cl 2

7. Single Displacement Reaction In a single displacement reaction, one element replaces a similar element in a compound. A + BX → AX + B How do you tell? element + compound → element + compound

8. Predicting the Products of Single Displacement Reactions K + CuSO 4  K + CuSO 4  K 2 SO 4 + Cu Cl 2 + NaBr  Cl 2 + NaBr  2NaCl + Br 2 Write compound formulas so charges cancel out!

9. Double Displacement Reaction In a double displacement reaction, ions from two compounds in solution exchange places to produce two new compounds. AB + CD → AD + CB How do you tell? compound + compound → compound + compound NaCl + AgNO 3  AgCl + NaNO 3

10. Predicting the Products of Double Displacement Reactions Na 2 S + HCl  Na 2 S + 2HCl  2NaCl + H 2 S Ca(NO 3 ) 2 + NaCl  Ca(NO 3 ) 2 + 2NaCl  2NaNO 3 + CaCl 2 Write compound formulas so charges cancel out!

11. Combustion Reaction In a combustion reaction (burning), a carbon compound combines with oxygen and releases a large amount of energy in the form of light and heat. Carbon compound + O 2 → CO 2 + H 2 O The products of a combustion reaction are ALWAYS CO 2 + H 2 O

12. Types of Reactions Practice Identify the following unbalanced reactions as synthesis, decomposition, single displacement, or double displacement. EXPLAIN YOUR CHOICE. 1. KOH + HBr → KBr + H 2 O 2. Mg + CO 2 → MgO + C 3.PCl 3 + Cl 2 → PCl 5

14. Type of Reaction Identifying the type…General Equation Synthesis Decomposition Single Displacement Double Displacement ONE compound is broken down to produce two or more compounds element + compound produces element + compound two compounds produce two compounds two or more reactants combine to produce ONE compound A + B → AB + → AB → A + B → + + → + A + BX → AX + B + → + AB + CD → AD + BC Combustion burning - carbon compound combines with oxygen to release heat/energy Carbon compound + O 2 → CO 2 + H 2 O ALWAYS THE PRODUCTS!

15. Types of Reaction Examples Synthesis: Mg + O 2  MgO Decomposition: KBrO 3  KBr + O 2 Single Displacement: Fe + CuSO 4  Cu + FeSO 4 Double Displacement: NaCl + AgNO 3  AgCl + NaNO 3 Combustion: C 6 H 14 + O 2 → CO 2 + H 2 O