IIIIIIIVV Ch. 8 – Chemical Reactions III. Types of Chemical Reactions (p )

1. Combustion CH 4 (g) + 2O 2 (g)  CO 2 (g) + 2H 2 O(g) n the burning of any substance in O 2 to produce heat A + O 2  B

C 3 H 8 (g)+ O 2 (g)  Combustion n Reactants:  contain oxygen n Products:  hydrocarbons form CO 2 + H 2 O CO 2 (g)+ H 2 O(g)

2. Synthesis n the combination of 2 or more substances to form a compound n only one product A + B  AB

Al(s)+ Cl 2 (g)  AlCl 3 (s) Synthesis n Products:  ionic - cancel charges  Reactants with O 2 or S, products are oxides or sulfides  Reactants with oxides and groups 1 or 2 metals, products are hydroxides

SYNTHESIS In the cartoon, the skinny bird (reactant) and the worm (reactant) combine to make one product, a fat bird

2. Synthesis Example C + O 2  CO 2 OO C +  OO C OO C O O C O O C O O C O O C O O C O O C O O C O O C O O C O O C O O C O O C General: A + B  AB

B. Synthesis H 2 (g) + Cl 2 (g)  2 HCl(g)

3. Decomposition n a compound breaks down into 2 or more simpler substances n only one reactant AB  A + B

KBr(l)  K(s) + Br 2 (l) Decomposition n Products:  binary - break into elements  Metal carbonates – metal oxides and CO 2 (g)  Metal hydroxides – EXCEPT Grp 1, metal oxides and H 2 O  Metal chlorides- chlorides and O 2 (g)

DECOMPOSITION In this cartoon the egg (the reactant), which contained the turtle at one time, now has opened and the turtle (product) and egg shell (product) are now two separate substances.

3. Decomposition 2 H 2 O(l)  2 H 2 (g) + O 2 (g)

3. Decomposition Example: NaCl General: AB  A + B  Cl Na Cl + Na

3. Decomposition Example 2 HgO  O Hg O OO + General: AB  A + B

4. Single Replacement n one element replaces another in a compound  metal replaces metal (+)  nonmetal replaces nonmetal (-) A + BC  B + AC

4. Single Replacement Cu(s) + 2AgNO 3 (aq)  Cu(NO 3 ) 2 (aq) + 2Ag(s)

Fe(s)+ CuSO 4 (aq)  Cu(s)+ FeSO 4 (aq) D. Single Replacement n Products:  free element must be more active (check activity series)  Metal in H 2 O – Group 1: hydroxides and H 2 (g). All others: oxides and H 2 (g)  Metal in acid – salt and H 2 (g) Br 2 (l)+ NaCl(aq)  N.R.

SINGLE REPLACEMENT Notice, the guy in the orange shirt steals the date of the other guy. So, a part of one of the reactants trades places and is in a different place among the products.

4. Single displacement Example: Zn + CuCl 2  Zn Cl Cu + General: AB + C  AC + B Cl Zn Cu +

AB + CD  AD + CB 5. Double Replacement n ions in two compounds “change partners” n cation of one compound combines with anion of the other

Pb(NO 3 ) 2 (aq)+ KI(aq)  PbI 2 (s)+ KNO 3 (aq) 5. Double Replacement n Products:  switch negative ions  one product must be insoluble (check solubility table) NaNO 3 (aq)+ KI(aq)  N.R. 2 2

5. Double displacement Example: MgO + CaS General: AB + CD  AD + CB S O  Mg Ca + O S Mg Ca +

5. Double Replacement Pb(NO 3 ) 2 (aq) + K 2 CrO 4 (aq)  PbCrO 4 (s) + 2KNO 3 (aq)

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