Types of Reactions Chapter 10

There are 5 Types of Reactions: 1. Synthesis 2. Decomposition 3. Single Displacement (replacement) 4. Double Displacement (replacement) 5. Combustion

Synthesis Reactions Occurs when two or more substances react to produce a single product Occurs when two or more substances react to produce a single product The new product must be a compound The new product must be a compound A + B  AB 2Na (s) + Cl 2 (g)  2NaCl (s) 2Na (s) + Cl 2 (g)  2NaCl (s)

Decomposition Reactions A compound is broken down by heat, electricity or light into two or more simpler products A compound is broken down by heat, electricity or light into two or more simpler products The products may be elements and/or compoundsAB  A + B The products may be elements and/or compoundsAB  A + B NH 4 NO 3 (s)  N 2 (g) + 2H 2 O (g) NH 4 NO 3 (s)  N 2 (g) + 2H 2 O (g) The decomposition of sodium azide, which produces a gas, is the key which produces a gas, is the key to inflatable airbags

Single Replacement Reactions Metals can only replace other metals provided they are below the metal they are trying to replace in the reactivity series Metals can only replace other metals provided they are below the metal they are trying to replace in the reactivity series A + BX  AX + B Mg + HCl  MgCl + H 2 A good example of a single replacement reaction is the use of Tums to neutralize stomach acid

Reactivity Series Helps determine if a reaction will occur Helps determine if a reaction will occur If the single element is higher on the list  yes a reaction will occur If the single element is higher on the list  yes a reaction will occur If the single element is lower on the list  NO REACTION If the single element is lower on the list  NO REACTION A + BX  AX + B Al + PbNO 3  Lithium Rubidium Potassium Calcium Sodium Magnesium Aluminum Manganese Zinc Iron Nickel Tin Lead Copper Silver Platinum Gold Fluorine Chlorine Bromine Iodine

Double Displacement Reactions The two positive ions (cations) exchange places between two compounds The two positive ions (cations) exchange places between two compounds This usually occurs between two ionic compounds in aqueous solution This usually occurs between two ionic compounds in aqueous solution AX + BY -> BX + AY CaCO 3 + H 2 SO 3 -> H 2 CO 3 + CaSO 4 This marble statue is becoming seriously eroded by acid rain (H 2 SO 3 ). When sulfurous acid (H 2 SO 3 ) comes in contact with marble (CaCO 3 ), a double displacement reaction occurs. The marble dissolves and leaves behind a white coating of calcium sulfate (CaSO 4 ) on the statue.

Combustion Reactions Oxygen reacts with a substance and releases energy in the form of heat and light (a substance is burned in oxygen2H 2 + O 2  2H 2 0 Oxygen reacts with a substance and releases energy in the form of heat and light (a substance is burned in oxygen2H 2 + O 2  2H 2 0 The Challenger disaster was a result The Challenger disaster was a result of a combustion reaction between hydrogen and oxygen Combustion reactions commonly involve hydrocarbons (substances that contain hydrogen and carbon) to produce carbon dioxide and water Combustion reactions commonly involve hydrocarbons (substances that contain hydrogen and carbon) to produce carbon dioxide and water C 8 H 18 + O 2 -> CO 2 + H 2 O + ENERGY Combustion reactions produce a large amount of energy Combustion reactions produce a large amount of energy