1. Chemical Equations reactants  products reactant- starting substance in a chemical reaction product- substance formed in a chemical reaction  = yields, gives you, produces, goes to **Law of Conservation of Mass holds true here mass of reactants = mass of products

2. -the states of matter can be indicated after the substance (s)=solid (ℓ)=liquid (g)=gas (aq)=aqueous = reversible reaction catalyst- substance that speeds up the rate of a reaction without being used up in the reaction **written above the arrow ex- Pt∆ = heat applied

3. **Remember H O N Cℓ Br I F skeleton equation- chemical equation that is not balanced ex- Write a skeleton for the following reaction: solid iron reacts with oxygen to form solid iron (III) oxide Fe(s) + O 2 (g)  Fe 2 O 3 (s)

4. Try these: 1) solid sodium hydrogen carbonate reacts with hydrochloric acid to produce aqueous sodium chloride, water and carbon dioxide 2)solid sulfur burns in oxygen to form sulfur dioxide 3)solid potassium chlorate forms oxygen and solid potassium chloride in the presence of catalyst manganese(II) oxide

5. Answers 1)NaHCO 3 (s) + HCℓ(aq)  NaCℓ(aq) + H 2 O (ℓ) + CO 2 (g) 2)S(s) + O 2 (g)  SO 2 (g) 3) KCℓO 3 (s) MnO O 2 (g) + KCℓ(s)

6. Balancing Equations -each side of the equation (reactants and products) must have the same # of each element -some may already be balanced -must be lowest whole # ratio -balance by putting coefficients in front of compounds

7. 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

8. Try these!! Don’t forget to balance!! a)aluminum + oxygen 4Aℓ + 3O 2  2Aℓ 2 O 3 b)copper + sulfur (two possible reactions) 2Cu + S  Cu 2 S or Cu + S  CuS c)beryllium + oxygen 2Be + O 2  2BeO d)strontium + iodine Sr + I 2  SrI 2 e) magnesium + nitrogen 3Mg + N 2  Mg 3 N 2

9. 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  b) hydrogen iodide  c) hydrogen bromide  d) sodium chloride 

10. a)PbO 2  Pb + O 2 b)2HI  H 2 + I 2 c)2HBr  H 2 + Br 2 d)2NaCℓ  2Na + 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

11. activity series of metals- lists metals in order of decreasing reactivity

12. 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 + 2Ag ex- Mg + LiNO 3  -lithium is above magnesium Mg + LiNO 3  no reaction

13. -Halogens can replace each other in single- replacement reactions -Reactivity decreases as you go down the halogen group Try These!! a) zinc + hydrogen sulfate  b) chlorine + sodium bromide  c) zinc + sodium nitrate  d) iron(II) + lead(II) nitrate  e) chlorine + sodium iodide 

14. a) Zn + H 2 SO 4  H 2 + ZnSO 4 b) Cℓ 2 + 2NaBr  Br 2 + 2NaCℓ c) Zn + NaNO 3  no reaction d) Fe + Pb(NO 3 ) 2  Pb + Fe(NO 3 ) 2 e) Cℓ 2 + 2NaI  I 2 + 2NaCℓ

15. 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  b)barium nitrate + hydrogen phosphate  c)potassium hydroxide+hydrogen phosphate  d)hydrogen sulfate + aluminum hydroxide 

16. Answers a)3NaOH + Fe(NO 3 ) 3  3NaNO 3 + Fe(OH) 3 b)3Ba(NO 3 ) 2 + 2H 3 PO 4  Ba 3 (PO 4 ) 2 + 6HNO 3 c)3KOH + H 3 PO 4  K 3 PO 4 + 3H 2 O d)3H 2 SO 4 + 2Aℓ(OH) 3  Aℓ 2 (SO 4 ) 3 + 6H 2 O

17. 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 any combustion begin with 2 in front of C x H y 2C 6 H 6 + 15O 2  12CO 2 + 6H 2 O *if all divisible by 2 then reduce

18. Try These!! a)C 14 H 26 + O 2  CO 2 + H 2 O b)C 8 H 12 + O 2  CO 2 + H 2 O Answers! a)2C 14 H 26 + 41O 2  28CO 2 + 26H 2 O b)C 8 H 12 + 11O 2  8CO 2 + 6H 2 O

19. 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