Chemical Reactions: Chapter 9 Reactants change chemical and physical properties …. to become new substances made from the same elements; these are called products.

Types of Reactions Synthesis or Composition Decomposition Single Replacement Double Displacement Combustion Reactions

Composition/ Synthesis Reactions A + X  AX An element may react with oxygen to form the oxide (oxidation) A X

Composition/ Synthesis Reactions O 2 + 2Mg  2 MgO oxygen reacts with magnesium to form magnesium oxide O Mg O

Composition/ Synthesis Reactions C + O 2  CO 2 carbon reacts with oxygen to form carbon dioxide O C O

Practice predicting reactions with oxide and sulfides 1.2Fe + ____  2FeO 2.4 Fe + 3 ___  Fe 2 O 3 3.S O 2  8 ____ 4.8 Ba + S 8  8 ____ O2O2 O2O2 SO 2 BaS

Metals react with halogens. 2Na + Cl 2  2 NaCl 2 Co + 3 F 2  2 CoF 3 2 K + I 2  2 KI Sr + Br 2  SrBr 2 2Mg + O 2  2 MgO

Synthesis reactions can also occur with oxides. Active metal oxides react with water to form hydroxides. ex: CaO + H 2 O  Ca(OH) 2 Many oxides of nonmetals react with water to form oxyacids. ex: SO 2 + H 2 O  H 2 SO 3 Some metal oxides react with nonmetal oxides to form salts. CaO + SO 2  CaSO 3

Practice Active metal oxides react with water to form hydroxides. ex: MgO + H 2 O  ________ Many oxides of nonmetals react with water to form oxyacids. ex: SO 3 + H 2 O  _________ Some metal oxides react with nonmetal oxides to form salts. MgO + NO 2  ________ Mg(OH) 2 H 2 SO 4 Mg(NO 3 ) 2

Decomposition AX  A + X 2H 2 O  2H 2 + O 2 O H H O H H Electrolysis: decomposition of a substance by an electric current.

Decomposition AX  A + X 2HgO  2Hg + O 2 O Hg O This reaction occurs when you heat orange colored mercury (II) oxide. Silver mercury and oxygen gas form.

Decomposition of metal carbonates ACO 3  AO + CO 2 (g) CaCO 3 (s)  CaO (s) + CO 2 (g) O Ca O This reaction occurs when you heat calcium carbonate. calcium oxide and carbon dioxide form. O C

Decomposition of metal hydroxides AOH  AO + CO 2 (g) Ca(OH) 2 (s)  CaO (s) + H 2 O (g) H Ca O This reaction occurs when you heat calcium hydroxide calcium oxide and water form. O H

Decomposition of metal chlorates AClO 3  ACl + O 2 (g) 2KClO 3 (s)  2KCl (s) + 3O 2 (g) K O This reaction occurs when you heat potassium chlorate. potassium chloride and oxygen form. Cl O K O O O O

Decomposition of acids H 2 CO 3 (aq)  H 2 O (g) + CO 2 (g) Carbonic acid decomposes when warmed. water and carbon dioxide form. O O O C H H

Single Displacement A+ BX  AX + B or: Y + BX  BY + X Replacement of a metal in a compound by another metal. 2 Al (s) + 3Pb(NO 3 ) 2  3Pb +2 Al(NO 3 ) 3 Al Pb 2+ N O O O N O O O N O O O N O O O N O O O N O O O

Single Displacement A+ BX  AX + B or: Y + BX  BY + X Replacement of a metal in a compound by another metal. 2 Al (s) + 3Pb(NO 3 ) 2  3Pb +2 Al(NO 3 ) 3 Al 3+ Pb N O O O N O O O N O O O N O O O N O O O N O O O

Single Displacement A+ BX  AX + B or: Y + BX  BY + X Replacement of a hydrogen in a compound by a metal. 2 Na (s) + 2 H 2 O (l)  2 NaOH (aq) + H 2 (g) Na O H H O H H

Single Displacement A+ BX  AX + B or: Y + BX  BY + X Replacement of a hydrogen in a compound by a metal. Mg (s) + 2 HCl (aq)  MgCl 2 (aq) + H 2 (g) Mg Cl H H

Single Displacement A+ BX  AX + B or: Y + BX  BY + X Replacement of halogens Cl 2 (g) + 2 KBr (aq)  2 KCl (aq) + Br 2 (g) Cl K Br K Cl

Double Replacement Reactions (double displacement) Formation of a precipitate. 2 KI (aq) + Pb(NO 3 ) 2 (aq)  PbI 2 (s) + 2 KNO 3 (aq) K K I Pb 2+ N O O O N O O O I

Double Replacement Reactions (double displacement) Formation of a gas. FeS (s) + 2 HCl(aq)  H 2 S (g) + FeCl 2 (aq) Fe 2+ S Cl H H

Double Replacement Reactions (double displacement) Formation of a water. NaOH (s) + HCl(aq)  H 2 O (g) + NaCl 2 (aq) Na + Cl H O H

Combustion Reactions A substance combines with oxygen, releasing a large amount of energy in the form of light and heat. 2 H 2 (g) + O 2 (g)  2 H 2 O O H H O H H

Combustion Reactions A substance combines with oxygen, releasing a large amount of energy in the form of light and heat. C 3 H 8 (g) +5 O 2 (g)  4 H 2 O + 3 CO 2 C CC H H H H H H H H O O O O O O O O O O

Combustion Reactions A substance combines with oxygen, releasing a large amount of energy in the form of light and heat. C 3 H 8 (g) +5 O 2 (g)  4 H 2 O + 3 CO 2 C C C H H H H H H H H O O O O O O O O O O