Day 2 Types of Chemical Reactions p. 114 - 118

**You have to be able to predict the products 5 major reaction types (there are more variations on these in reality) Synthesis Decomposition Single replacement Double replacement (including neutralizations) Combustion **You have to be able to predict the products in each case **

Synthesis (aka combination) A + B → AB Combining 2 or more substances to form a new compound eg. 2 Sb(s) + 3Br2(g) → 2SbBr3(g) H2(g) + Cl2(g) → HCl(g) try: C(s) + O2(g) → CO2(g)

Synthesis (aka combination) How to Recognize: only elements as reactants Predicting products (for rxs involving 2 elements): Assume product will be an ionic compound made of both elements (or something recognizable such as CO2) Use the most common charges for each ion (the top one on the periodic table) when making your formula

common charge = top charge

Decomposition AB → A + B = breaking down a molecule into simpler substances ( = chemical separation!) eg. 2 Ag2O(s) + heat → 4Ag(s) + O2(g) 2 HgO(s) + heat → 2Hg(l) + O2(g) try: 2 NO(g) + heat → N2(g) + O2(g)

Decomposition How to recognize: only one reactant! Predicting products: Assume the reactant breaks into its component elements try: 2H2O(l) → 2H2(g) + O2(g)

Single Replacement AB + C → A + CB (if C is a metal) AB + C → AC + B (if C is a non-metal) = replacing one atom in a compound with another atom. (like you are dancing with a friend and someone cuts in) someone is always single! *Watch out for Polyatomic ions*

Single Replacement How to Recognise: Reactants = one element and one compound Predicting Products: The compound = metal + non-metal The element may be either metal or non-metal * Metals trade with metals * Non-metals trade with non-metals

Single Replacement eg. CuI2(s) + Br2(l) → CuBr2(s) + I2(s) try: Cl2(aq) + 2 KI(aq) → 2 KCl(aq) + I2(aq) try: 2 AgNO3(aq) + Cu(s) → 2 Ag(s) + Cu(NO3)2(aq)

(like two couples dancing and then a partner swap) Double Replacement AB + CD → AD + CB = an exchange of atoms or groups between two different compounds (like two couples dancing and then a partner swap)

Double Replacement eg. AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq) Try: 2 NaCl(aq) + H2SO4(aq) → 2 HCl(aq) + Na2SO4(aq)

Double Replacement How to recognize: two compounds react Predicting products: Assume the reactants are made up of ions Swap positive ions Watch charges when making new compounds = nomenclature/formula writing!!** Try: Cu(NO3)2(aq) + Na2S(aq) → CuS(s) + 2NaNO3(aq)

Acid Base Neutralization = Double Replacement Acid + Base → Salt + H2O Acid = chemical formula starts with H Base = chemical formula ends with OH Salt = ionic compound that is not an acid, or a base i.e. does not start with H does not end with OH

Acid or Base or Salt?? HCl KOH NaNO3 H2SO4 Ba(OH)2 Fe(OH)3 K2SO4 LiCl Acid Base Salt

Acid Base Neutralization e.g. HCl(aq) + NaOH(aq) → H2O(l) + NaCl(aq) Try: H2SO4(aq) + 2 KOH(aq) → K2SO4(aq) + 2 H2O(l) 2 H3PO4(aq) + 3 Sr(OH)2(aq) → Sr3(PO4)2(aq)+ 3 H2O(l)

Acid Base Neutralization *** Notice that H2O = HOH (this should help you with your balancing) HCl(aq) + NaOH(aq) → HOH(l) + NaCl(aq) H2SO4(aq) + 2 KOH(aq) → K2SO4(aq) + 2 HOH(l) 2 H3PO4(aq) + 3 Sr(OH)2(aq) → Sr3(PO4)2(aq)+ 6 HOH(l)

Combustion CxHyOZ + O2(g) → CO2(g) + H2O(g) = the rapid reaction of a substance with oxygen producing heat and often flames!

Combustion How to recognize: look for a hydrocarbon reactant (CxHyOZ) Predicting Products: you don’t have to! It will always be CO2(g) and H2O(g) but you do have to balance the rx!

C5H12(l) + 8 O2(g) → 5 CO2(g) + 6 H2O(g) Combustion Try: C5H12(l) + 8 O2(g) → 5 CO2(g) + 6 H2O(g) C5H12O2(l) + 7 O2(g) → 5 CO2(g) + 6 H2O(g) cv cv

Notes: Add to your notes the table on page 118. Feel free to modify it in your own words Practice: p. 118 # 65, 66, 67 (especially 67)