Topic: Chemical Reactions Do Now:

Physical vs. Chemical Change Physical Change = Chemical Change = Change in form/appearance Examples: Dissolving & phase changes Change in identity Change in formula representing a substance

Evidence of a Chemical Reaction Temperature change Emission of Light Energy Change in identifying property: Color, mp, bp, density, Hf, Hv, c … Formation of Gas Bubbling, odor Formation of Solid Precipitate

Chemical Equations A + B  C + D Left Side = Reactants (starting materials) Right Side = Products (ending materials) “” is read as produces/yields How do we show the physical state of the reactants & products? (s), (l), (g), (aq)

Types of Reactions Synthesis Decomposition Single Replacement Double Replacement Combustion

Synthesis Format: A + B  C Identifying feature: 1 product only Note: A and B may be elements or compounds, C is a compound 2 Fe(s) + 3 Cl2(g)  2 FeCl3(s) CaO(s) + H2O(l)  Ca(OH)2(s)

Decomposition Format: AB  A + B Identifying feature: 1 reactant only Note: A & B may be elements or compounds 2 NaN3(s)  2 Na(s) + 3 N2(g) NH4NO3(s)  N2O(g) + 2 H2O(g)

Single Replacement Format: A + BX  AX + B Identifying Feature: Element + Compound  Different Element + Different Compound 2 Li(s) + 2 H2O(l)  2 LiOH(aq) + H2(g) Cu(s) + 2AgNO3(aq)  2Ag(s) + Cu(NO3)2(aq)

Double Replacement Format:AX + BY  AY + BX Identifying feature: 2 compounds yield 2 new compounds Ca(OH)2(aq) + 2HCl(aq)  CaCl2(aq) + 2 H2O(l) 2 NaOH(aq) + CuCl2(aq)  2 NaCl(aq) + Cu(OH)2(s)

Combustion or Reaction with O2 Format: A + O2  B ( + C + …) Identifying feature: One of reactants is O2 Note: A can be an element or a compound, usually more than 1 product CH4(g) + 2 O2(g)  CO2(g) + 2 H2O(g) For Regents synthesis TOPS combustion: 2 H2(g) + O2(g)  2 H2O(g) C(s) + O2(g)  CO2(g)

Identify the Reaction Type CaO + CO2  CaCO3 2 H2O  2 H2 + O2 NaOH + HCl  NaCl + H2O Zn + 2 HCl  ZnCl2 + H2 2 Mg + O2  2 MgO Mg + H2SO4  MgSO4 + H2 2 KClO3  2 KCl + 3 O2 AgNO3 + NaCl  NaNO3 + AgCl C2H6 + O2  CO2 + H2O Synthesis Decomposition DR SR Synthesis SR Decomposition DR Combustion