Chapter 8 Section 2 **Remember H O N Cℓ Br I F Types of Chemical Reactions 1)Combination/Synthesis Reaction -two or more substances combine to form a single substance reactants- two elements or two compounds products- always a compound ex-2K + Cℓ 2 → 2KCℓ ex- SO 2 + H 2 O → H 2 SO 3

Try these!! Don’t forget to balance!! a) aluminum + oxygen → Aℓ + O 2 → Aℓ + O 2 → Aℓ 2 O 3 b) beryllium + oxygen → Be + O 2 → Be + O 2 → BeO c) strontium + iodine → Sr + I 2 → Sr + I 2 → SrI 2 d) magnesium + nitrogen → Mg + N 2 → Mg + N 2 → Mg 3 N 2

2)Decomposition Reaction -one compound breaks down or decomposes into two simpler compounds -the reverse of synthesis ex- 2H 2 O → 2H 2 + O 2 Try these!! a) lead(IV) oxide → PbO 2 → PbO 2 → Pb + O 2 b)hydrogen iodide → HI → HI → H 2 + I 2

c) hydrogen bromide → HBr → HBr → H 2 + Br 2 d) sodium chloride → NaCℓ → NaCℓ → Na + Cℓ 2

3)Single-Replacement Reactions -one element replaces a second element in a compound ex- 2K + CaO → K 2 O + Ca -whether one metal will replace another metal is determined by reactivity of the metal activity series of metals- lists metals in order of decreasing reactivity **Page 217 -a metal will replace another metal listed below it in the table

ex- Mg + Zn(NO 3 ) 2 → *is Mg above Zn on the reactivity series? Mg + Zn(NO 3 ) 2 → Mg(NO 3 ) 2 + Zn ex- Mg + Ag 2 SO 4 → Mg + Ag 2 SO 4 → MgSO 4 + Ag ex- Mg + LiNO 3 → -lithium is above magnesium Mg + LiNO 3 → no reaction (NR)

-Halogens can replace each other in single- replacement reactions -Reactivity decreases as you go down the halogen group Try These!! a)zinc + hydrogen sulfate → Zn + H 2 SO 4 → Zn + H 2 SO 4 → H 2 + ZnSO 4 b)chlorine + sodium bromide → Cℓ 2 + NaBr → Cℓ 2 + NaBr → Br 2 + NaCℓ

c) zinc + sodium nitrate → Zn + NaNO 3 → no reaction d) iron(II) + lead(II) nitrate → Fe + Pb(NO 3 ) 2 → Fe + Pb(NO 3 ) 2 → Pb + Fe(NO 3 ) 2 e) chlorine + sodium iodide → Cℓ 2 + NaI → Cℓ 2 + NaI → I 2 + NaCℓ

4)Double-Replacement Reactions -involve an exchange of cations between two reacting compounds ex- BaCℓ 2 + K 2 CO 3 → BaCO 3 + 2KCℓ ex- FeS + 2HCℓ → H 2 S + FeCℓ 2 Try These!! a)sodium hydroxide + iron(III) nitrate → NaOH + Fe(NO 3 ) 3 → NaOH + Fe(NO 3 ) 3 → NaNO 3 + Fe(OH) 3

b)barium nitrate + hydrogen phosphate → Ba(NO 3 ) 2 + H 3 PO 4 → Ba(NO 3 ) 2 + H 3 PO 4 → Ba 3 (PO 4 ) 2 + HNO 3 c)potassium hydroxide+hydrogen phosphate → KOH + H 3 PO 4 → KOH + H 3 PO 4 → K 3 PO 4 + H 2 O d) hydrogen sulfate + aluminum hydroxide → H 2 SO 4 + Aℓ(OH) 3 → H 2 SO 4 + Aℓ(OH) 3 → Aℓ 2 (SO 4 ) 3 + H 2 O

5)Combustion Reaction -hydrocarbon combined with oxygen to produce carbon dioxide and water ex- C 6 H 6 + O 2 → CO 2 + H 2 O -to balance: *always begin with a 2 in front of hydrocarbon *when done, if can divide by 2 do so 2C 6 H O 2 → 12CO 2 + 6H 2 O

Try These!! a)C 14 H 26 + O 2 → 2C 14 H O 2 → 28CO H 2 O b)C 8 H 12 + O 2 → 2C 8 H O 2 → 16CO H 2 O C 8 H O 2 → 8CO 2 + 6H 2 O

Summary of Reactions 1)Combination/Synthesis R + S → RS 2)Decomposition Reaction RS → R + S 3)Single-Replacement Reaction T + RS → R + TS 4)Double-Replacement Reaction RS + TU → RU + TS 5)Combustion Reaction C x H y + O 2 → CO 2 + H 2 O