Types of Chemical Reactions Identifying the Reactions Notes

Types of Chemical Reactions Chemists classify chemical reactions into 5 main types This helps to recognize patterns and predict the products 5 Types: Synthesis Decomposition Combustion Single Displacement Double Displacement

Synthesis

Synthesis Reactions Definition: Two or more substances react to form a single substance SIMPLER substances combine to form one COMPLEX substance General Equation: A + B  AB To Identify: Has one product (a compound) Example: 2 Ca + O2  2 CaO

Synthesis Examples Two elements react to form one compound. 2 Mg+ O2  2 MgO Two compounds react to form one compound. CaO + H2O  Ca(OH)2 One compound and an element react to form one compound. 2 SO2 + O2  2 SO3

Synthesis Analogy It is like a relationship or marriage +

Decomposition

Decomposition Reactions Definition: A single compound breaks down into two more simpler substances The reverse of a synthesis reaction General Equation: AB  A + B To Identify: Has one reactant (a compound) Example: H2CO3  H2O + CO2

Decomposition Examples Metal carbonates produce metal oxides and carbon dioxide Na2CO3-->Na2O + CO2 Metal hydroxides produce metal oxides and water Ca(OH)2-->CaO + H2O Metal chlorates produce metal chlorides and oxygen gas KClO3-->KCl + O2 Oxyacids produce water and a nonmetal oxide gas 2HNO3-->H2O + N2O5 Metal oxides produce metals and oxygen gas Au2O3--> O2 + Au Water can produce oxygen gas and hydrogen gas H2O--> H2 + O2

Decomposition Analogy It is like a breakup or divorce +

Combustion

Combustion Reactions Definition: A hydrocarbon reacts with oxygen to produce water and carbon dioxide General Equation: CxHy +O2  CO2 + H2O To Identify: O2 in reactants, CO2 and H2O in products Example: CH4 + 2 O2  CO2 + 2 H2O

Single Displacement

Single Displacement Reactions Definition: One element replaces a second element in a compound General Equation: A + BC  AC + B To Identify: On each side of the equation, you will see one element and one compound Example: Cu + 2AgNO3  Cu(NO3)2 + 2Ag

Single Displacement Examples Types of SR Reactions Metal replaces another metal Mg + CuCl2  MgCl2 + Cu Metal replaces hydrogen 2 Li + H2O  H2 + Li2O Nonmetal replaces nonmetal F2 + 2NaBr  2NaF + Br2

Single Displacement Reactions Whether displacement will occur depends on reactivity of elements Use activity series The more reactive element can replace the less reactive element If a less reactive element tries to replace a more reactive element then no reaction

Single Displacement Analogy It is like getting divorced and finding a new spouse OR breaking up and finding a new girlfriend/boyfriend Dancing analogy + +

Double Displacement

Double Displacement Reactions Definition: Involves an exchange of negative ions between two compounds Often take place in aqueous solutions and produce a precipitate A solid that is produced from liquid solution General Equation: AB + CD  AD + CB To Identify: On each side of the equation, you will see two compounds Example: 2 NaOH + CuCl2  2 NaCl + Cu(OH)2

Double Displacement Analogy Dancing with two couples and you switch partners

Reactions Summary Table Type of Reaction Reactants Probable Products Generic Equation Synthesis 2 or more substances One compound A + B  AB Decomposition AB  A + B Combustion Hydrocarbon & oxygen CO2 + H2O CxHy + O2  CO2 + H2O Single Replacement Metal & compound Nonmetal & compound New compound & replaced metal New compound & replaced nonmetal A + BX  AX + B Double Replacement Two compounds Two different compounds AX + BY  AY + BX