Types of Reactions

Types of Reactions There are five types of chemical reactions we will talk about. Combustion reactions Synthesis reactions Decomposition reactions Single replacement reactions Double replacement reactions

__CH3CH2OH + __O2  __CO2 + __H2O Who wants to see a demo? 1 2 7 4 2 3 6 __CH3CH2OH + __O2  __CO2 + __H2O 3.5 x 2

Combustion Reactions occur when a hydrocarbon reacts with oxygen gas (a.k.a. burning) need the 3 things in the “fire triangle”: 1) A Fuel (hydrocarbon) 2) Oxygen to burn it with 3) Something to ignite the reaction (spark)

Combustion Formula: CxHy + O2  CO2 + H20 Look for a Hydrocarbon and O2 in the reactants Look for CO2 and H2O in the products

__C4H4 + __O2  __C4H8 + __O2  __C4H10 + __O2  Practice: __CO2 + __H2O __CO2 + __H2O __CO2 + __H2O __C4H4 + __O2  __C4H8 + __O2  __C4H10 + __O2  1 5 4 2 6 4 4 1 2 1 8 4 10 5 13 6.5 x2 x2 x2 x2

DEMO __Mg + __O2  __MgO

Synthesis reactions A + B  AB Analogy: marriage, baking occur when two substances (generally elements) combine and form a compound (sometimes these are called combination or addition reactions) reactant + reactant  1 product Example: 2H2 + O2  2H2O Example: C + O2  CO2

Al+3 O-2 3 2 4 2 Na+1 I-1 2 1 2 Practices __ Al2O3   __ O2 (g) + __ Al (s)  __ Na (s) + __ I2 (l)  Na+1 I-1 __ NaI 2 1 2

Wanna see a gummy bear dance? 2 2 3 __KClO3  __KCl + __O2

Decomposition Reactions AB  A + B Analogy: divorce occur when a compound breaks up into the elements or to simpler compounds 1 Reactant  Product + Product Example: 2 H2O  2H2 + O2 Example: 2 HgO  2Hg + O2

2 2 4 3 2 1 2 2 1 2 Diatomic! Practices Practice 1: __ Al2O3 (s)    Practice 2: __ CuO (s)  Practice 3: __ H2O (l)  ___ Al +   ___ O2   2 1 2 ___ Cu +   ___ O2   2 1 2 ___ H2 +   ___ O2   Diatomic!

Another demo, shall we? ___ Cu + ___ AgNO3  ___Ag + ___Cu(NO3)2

Single Replacement Reactions A + BC  AC + B (if A is metal) Analogy: “homewrecker” occur when one element replaces another in a compound A metal can replace a metal (ca+ion) element + compound product + product Zn + 2HCl  ZnCl2 + H2 Prediction: First identify if the single element is a METAL (will replace the cation in the compound) Next, is the single element more reactive than the one it is trying to replace? Look at “Activity Series of Metals” list

1 2 1 1 1 2 1 1 NR   Practices Homework: ___ Mg (s) + ___ HNO3 (aq)    ___ Zn (s) + ___ HCl (l)  ___ FeBr3 (s) + ___ Ag (s)  Homework: Practice – Single Replacement Determine reaction or no reaction (NR) If reaction, balance ___ H2 + ___ Mg(NO3)2 1 2 1 1 ___ H2 + ___ ZnCl2 NR  

One more demo… ___Pb(NO3)2 + ___KI  ___PbI2 + ___KNO3 1 2 1 2

Double Replacement Reaction AB + CD  AD + CB Analogy: Flintstones couple switch occur when a metal replaces a metal in a compound or a nonmetal replaces a nonmetal in a compound compound + compound  product + product Ex: AgNO3(aq) + NaCl(s)  AgCl(s) + NaNO3(aq)

Double Replacement Reactions Think about it like “foil”ing in algebra, first and last ions go together & inside ions go together Example: AgNO3(aq) + NaCl(s)  AgCl(s) + NaNO3(aq) Another example: K2SO4(aq) + Ba(NO3)2(aq)  KNO3(aq) + BaSO4(s) 2

Prediction break both compounds into their CATIONS and ANIONS trade partners & write your two new formulas but REMEMBER: CA+ION always goes first Assign charges; SWAP & DROP. If one reactant ends in (OH) and one starts w/ H one of the products is water (H2O) Test solubility and see which product is the precipitate (if any) and which stays in solution (aq). if both stayed in solution (aq) we would write NO REACTION

YES NO AgNO3(aq) + NaCl(s)  AgCl(s) + NaNO3(aq) Precipitate formed?

KBr(aq) + AlPO4(aq)  K3PO4(aq) + AlBr3(aq) Precipitate formed? NO

Acid-Base (Neutralization) A special kind of double replacement ACID + BASE  Salt + H2O (l) Ex. HCl + NaOH → NaCl + H2O Ex. H2SO4 + Mg(OH)2 → MgSO4 + H2O

Practice 2 1 1 1 1. __CaCO3 + __HCl → 2. __KOH + __H2SO4 → 3. __Pb(NO3)2 + __K2S → __CaCl2 + __H2CO3 2 1 1 2 __K2SO4 + __H2O 1 1 2 1 __KNO3 + __PbS

Classify each: synthesis single repl. combustion decomposition CaO + H2O ----> Ca(OH)2 Cl2 + KBr ----> KCl + Br2 CH4 + O2 ----> H2O + CO2 Ag2O ----> Ag + O2 AgNO3 + NaCl ----> AgCl + NaNO3 single repl. combustion decomposition double repl.