Unit VI: CHEMICAL REACTIONS I.5. Types Of Chemical Reactions

Types of Reactions 1. Synthesis 2. Decomposition 3. Single Replacement 4. Double Replacement Neutralization (Water Forming) 5. Combustion 1. Combustion of hydrocarbons 2. Combustion of metals

Synthesis Two or more substances combine to form a compound A + B → AB

Synthesis Often:  elements  a compound 2Al + 3F 2  2AlF 3

Synthesis Examples  2H 2 + O 2 → 2H 2 O  2Mg + O 2 → 2MgO  CaO + CO 2 → CaCO 3

Synthesis potassium + oxygen  calcium + phosphorous 

Synthesis A special type of synthesis CoCl 2 + 6H 2 O  CoCl 2 ● 6H 2 O

Synthesis A compound + an element  a “bigger” compound 2SO 2 + O 2  2SO 3

Synthesis - Overview Always m mm more than 1 reactant Usually forms only 1 product

Decomposition One substance breaks down into more than one substance AB → A + B

Decomposition

EXAMPLES:  2HgO → 2Hg + O 2  2H 2 O → 2H 2 + O 2  MgCl 2 → Mg + Cl 2

Decomposition Note: Unless otherwise told, break all compounds COMPLETELY down to its elements. (Even break up PAIs)

Decomposition A special type of decomposition CuSO 4 ● 5H 2 O  CuSO 4 + 6H 2 O

Decomposition Also A Bigger Compound  Smaller Compound + An Element 2KClO 3  2KCl + 3O 2

Single Replacement One substance replaces another in a compound  Metals replace metals  Non-metals replace non-metals AB + C → A + BC

Single Replacement Two Types 1. Metal Single Replacement 2. Non-metal Single Replacement

Single Replacement Examples of Metal SR Zn + CuSO 4 → Cu + ZnSO 4 Fe + 3AgNO 3 → 3Ag + Fe(NO 3 ) 3

Single Replacement Metal SRs

Single Replacement Some Non-Metal SRs

Single Replacement The catch some elements are not strong enough to replace others Plan: 1. Predict Products 2. Fix Formulas 3. Balance Equation 4. Determine from Activity Series if Reaction will Proceed

Single Replacement Refer to the activity series to determine the relative reactivity of elements. For example, calcium is more reactive than hydrogen; therefore, calcium can replace hydrogen in a reaction.activity series Ca(s) + 2 HOH(l)  Ca(OH) 2 (s) + H 2 (g)

Double Replacement Both compounds change partners Again refer to the activity series to see if reaction will proceed AB + CD → AD + BC

Double Replacement Examples:  2KI (aq) + Pb(NO 3 ) 2 (aq) → 2KNO 3 (aq) + PbI (s)  AgNO 3 + KCl → AgCl(s) + KNO 3

Neutralization Sub-type of Double Replacement Reaction Sometimes called water forming ACID + BASE → WATER + SALT

Neutralization

Combustion (aka Burning Stuff) Substance reacts with oxygen (fast enough to produce heat and light) Two Types of Combustion 1. Combustion of hydrocarbons 2. Combustion of metals

Combustion Hydrocarbons ALWAYS A REACTANT  NOTE: O 2 is ALWAYS A REACTANT! ASSUME  When burning hydrocarbons ASSUME the products are CO 2 + H 2 O

Combustion C x H y + O 2 → CO 2 + H 2 O

Combustion

Combustion of Metals = Synthesis

Lab Do Experiment 5C – page 71-73[Heath] before  This experiment will take most of the class your pre-lab must be complete before the lab begins  Fill in the Blank Lab Format you are only responsible for the questions asked in the lab handout