Types of Chemical Reactions Learning Target: To be able to identify the different type of reactions when looking at skeletal equations

There are 5 types of Reactions: Synthesis Decomposition Single-replacement Double-replacement Combustion

Synthesis: A chemical rxn in which 2 or more substances (A + B) react to produce a single product (AB) A + B ⇒ AB Na(s) + Cl2(g) ⇒ NaCl(s) SO2(g) + O2(g) ⇒ SO3(g) You can spot a synthesis reaction because there is only 1 product.

AB ⇒ A + B NH4NO3(s) ⇒ N2O(g) + H2O(g) Na3N(s) ⇒ Na(s) + N2(g) Decomposition: A rxn in which a single compound (AB) breaks down into 2 or more new substances (A + B…) AB ⇒ A + B NH4NO3(s) ⇒ N2O(g) + H2O(g) Na3N(s) ⇒ Na(s) + N2(g) You can identify a decomposition rxn because there is only one reactant.

A + BX ⇒ AX + B Li(s) + H2O(l) ⇒ LiOH(aq) + H2(g) Single Replacement: A rxn in which the atoms of one element replace the atoms of another element in a compound A + BX ⇒ AX + B Li(s) + H2O(l) ⇒ LiOH(aq) + H2(g) Cu(s) + AgNO3(aq) ⇒ Ag(s) + Cu(NO3)2 In single replacement the metal with the higher activity will replace the metal with the lower activity. You can spot a single replacement reaction by the single element on each side of the equation. Think of your friend stealing your boyfriend/girlfriend from you, and you are left by yourself.

Activity Series: Single Replacement Rxn Active metals will replace less active metals in reactions. Pt(s) + Zn2O (aq) → NR Fe(s)  +  CuSO4(aq)  →    FeSO4(aq)  +  Cu(s) Na(s) + SnCO3(aq) → Na2CO3(aq) + Sn(s)

AX + BY ⇒ AY + BX Ca(OH)2(aq) + HCl(aq) ⇒ CaCl2(aq) + H2O(l) Double Replacement: a rxn which involves an exchange of ions between 2 compounds AX + BY ⇒ AY + BX *Either the metals change places or the nonmetals change places but not both!!! Ca(OH)2(aq) + HCl(aq) ⇒ CaCl2(aq) + H2O(l) *Typically occurs in aqueous solutions (in water) NaOH(aq) + CuCl2(aq) ⇒ NaCl(aq) + Cu(OH)2(s) *Precipitate: Is when a solid forms from a solution You can identify double replacement by the two compounds on each side of the equation.

3 Types of Double Replacement: Formation of a precipitate Formation of H2O Formation of a product which decomposes into a gas

Double-Replacement: Formation of a precipitate Solubility Rules: Some compounds will dissolve in water (soluble) Some will NOT dissolve in water (insoluble/ not soluble) If during a double-replacement rxn, a solid is formed, it will fall out of the solution. This is called a precipitate. Ex: Cd(SO4)(aq) + K2S(aq) CdS(s) + K2 (SO4)(aq)

Double-Replacement: Formation of H2O These occur between Acids and Bases Acids ALWAYS start with _________ Bases are compounds that end with hydroxides (OH-) One product will be H2O and one will be an ionic salt compound HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) *Some people consider this a separate rxn altogether

CH4(g) + O2(g) ⇒ CO2(g) + H2O(l) Combustion: a rxn in which O2 can combine with a substance to release energy Ex: Fire, Burning, etc. C(s) + O2(g) ⇒ CO2(g) CH4(g) + O2(g) ⇒ CO2(g) + H2O(l) *In most cases, the products will be H2O and CO2

Practice Problems: Complete these in your notes, I will call students up to share their answers. _________________________C2H6(g) + O2(g) → H2O(g) +CO2(g) _________________________ Br2(l) + LiI(s) → LiBr + I2(s) _________________________ Fe(s) + H2O(l) →Fe3O4(s) + H2(g) _________________________ MgCO3(s) → MgO(s) + CO2(g) _________________________ P4(s) + O2(g) → P4O10(s) _________________________ KNO3(s) → KNO2(s) + O2(g) _________________________ KOH + H3PO4 →K3PO4 + H2O _________________________ Na(s) + O2(g) →Na2O(s) _________________________ O2(g) + C6H12O6(g) → H2O(g) + CO2(g)