Reaction Types

CHEMICAL REACTION Chemical Reaction: a process in which substances change into other substances.

CHEMICAL REACTION You know a chemical reaction has taken place is one or more of these occur: Color change Heat content changes Gas is produced Precipitate forms

General: A + B  AB Types: Synthesis Two or more substances combine to form a new compound. Example C + O2 O C O C +  O C O C O C O C O C O C O C O C O C O C O C O C O C O C General: A + B  AB

Synthesis (Combination) Reactions Two or more substances combine to form a new compound. A + X  AX hydrogen and nonmetal  binary acid H2 + F2  2HF (hydrofluoric acid) Metal – nonmetal  binary ionic compound 2Na + Cl2  2NaCl Metal oxide – water  metal hydroxide CaO + H2O  Ca(OH)2 Nonmetal oxide – water  oxyacid SO3 + H2O  H2SO3

Decomposition Reactions A single compound undergoes a reaction that produces two or more simpler substances AX  A + X Decomposition of: Binary compounds H2O(l )  2H2(g) + O2(g) Metal carbonates CaCO3(s)  CaO(s) + CO2(g) Metal hydrogen carbonates NaHCO3 Na2O +H2O +CO2 Metal hydroxides Ca(OH)2(s)  CaO(s) + H2O(g) Metal chlorates 2KClO3(s)  2KCl(s) + 3O2(g) Oxyacids H2CO3(aq)  CO2(g) + H2O(l ) Hydrate CuSO4 ●5 H2O  CuSO4 + 5H2O Be able to use your reference tables.

Combustion Reactions A hydrocarbon combines with oxygen, releasing a large amount of energy in the form of light and heat, producing carbon dioxide and water. Hydrocarbon – a compound containing only carbon, hydrogen and sometimes oxygen. CH4(g) + 2O2(g)  CO2(g) + 2H2O(g) C3H8(g) + 5O2(g)  3CO2(g) + 4H2O(g) Hydrocarbon + oxygen  carbon dioxide + water These can be very challenging to balance!

Single Replacement Reactions Cation Replacement A + BX  AX + B B B X X A A +  + O Anion Replacement BX + Y  BY + X  B B X X Y Y + +

Single Replacement Reactions A + BX  AX + B BX + Y  BY + X Replacement of: Metals by another metal Hydrogen in water by a metal Hydrogen in an acid by a metal Halogens by more active halogens

The Activity Series of the Metals Lithium Potassium Calcium Sodium Magnesium Aluminum Zinc Chromium Iron Nickel Lead Hydrogen Bismuth Copper Mercury Silver Platinum Gold Metals can replace other metals provided that they are above the metal that they are trying to replace Metals above hydrogen can replace hydrogen in acids. Metals from sodium upward can replace hydrogen in water

The Activity Series of the Halogens Halogens can replace other halogens in compounds, provided that they are above the halogen that they are trying to replace. Fluorine Chlorine Bromine Iodine 2NaCl(s) + F2(g)  ??? 2NaF(s) + Cl2(g) MgCl2(s) + Br2(g)  ??? No Reaction

No, Ni is below Na Yes, Li is above Zn Yes, Al is above Cu We have looked at several reactions: Fe + CuSO4  Cu + Fe2(SO4)3 Li + H2O  LiOH + H2 Such experiments reveal trends. The activity series ranks the relative reactivity of metals. It allows us to predict if certain chemicals will undergo single displacement reactions when mixed: metals near the top are most reactive and will displacing metals near the bottom. Q: Which of these will react? Fe + CuSO4  Ni + NaCl  Li + ZnCO3  Al + CuCl2  K Na Li Ca Mg Al Zn Fe Ni Sn Pb H Cu Hg Ag Au No, Ni is below Na Yes, Li is above Zn Yes, Al is above Cu Yes, Fe is above Cu Cu + Fe2(SO4)3 NR (no reaction) Zn + Li2CO3 Cu + AlCl3

A: No for cold, yes if it is hot/steam Mg + H2O  H2 + Mg(OH)2 acid H is the only nonmetal listed. H2 may be displaced from acids or can be given off when a metal reacts with H2O (producing H2 + metal hydroxide). The reaction with H2O depends on metal reactivity & water temp. Q: will Mg react with H2O? K Na Li Ca Mg Al Zn Fe Ni Sn Pb H Cu Hg Ag Au cold H2O hot H2O steam A: No for cold, yes if it is hot/steam Mg + H2O  H2 + Mg(OH)2 acid Q: Zn + HCl  H2 + ZnCl2 Complete these reactions: Al + H2O(steam)  Cu + H2O  Ca + H2SO4  Na + H2O  H2 + Al(OH)3 NR H2 + CaSO4 H2 + NaOH

Other Activity Series Information All metals will have a specific place in the activity series. For simplicity, only the most common metals are shown. The metals near the top of the activity series are more reactive because their valence electrons are more easily removed. On tests and exams the activity series may appear as K, Na, … Ag, Au; you must remember that K is reactive, Au is not.

Activity series lab Place the acetate sheet down on the lab table in front of you over the data table. (A) Place a few drops of copper (II) nitrate solution in rows 2 through 4 in the first column (marked Cu2+(aq)). (B) Put a few drops of magnesium nitrate in rows 1, 3, and 4 of the second column (marked Mg2+(aq)). Continue C – E. Put a small piece of copper metal in each of the squares containing solution in the first row. Add magnesium metal to the solutions in the second row, etc… Allow to stand at least 3 minutes. (A) Determine if a reaction has occurred in each well by observing if a metal precipitate has formed or if the surface of the metal has become coated or corroded. (B) If a metal ion is reduced by a metal then the reverse reaction should not occur. (C) One metal is more reactive than another if the metal will replace the metal ion (reduce it) in its compounds. (D) Record your observations in the data table below.

 Cu2+(aq) Mg2+(aq) Pb2+(aq) Zn2+(aq) Ag1+(aq) Cu Mg Pb Zn Mg + AgNO3  Ag+ Mg(NO3)2 Pb Zn 

Double Replacement Reactions The ions of two compounds exchange places in an aqueous solution to form two new compounds. AX + BY  AY + BX +  + A A X X B B Y Y

Double Replacement Reactions The ions of two compounds exchange places in an aqueous solution to form two new compounds. AX + BY  AY + BX One of the compounds formed is usually a precipitate, an insoluble gas that bubbles out of solution, or a molecular compound, usually water.

Typhoid Who? Select a test tube. Draw up about 1 mL of solution into a pipette. Exchange the solution with a peer on the teachers directions. Repeat with 2 more students. Get a drop of AgNO3 from the instructor. Who was the original contaminate?