Types of Chemical Reactions

Transcription

1 Types of Chemical Reactions A) DECOMPOSTION AB A + B During a decomposition reaction, one compound splits into two or more pieces. These smaller pieces can be elements or simpler compounds. magnesium chloride magnesium + chlorine calcium carbonate calcium oxide + oxygen potassium chlorate potassium chloride + oxygen iron(iii) hydroxide iron (III) oxide + water carbonic acid carbon dioxide + water 2 H 2 O 2 H 2 + O 2 Na 2 CO 3 Na 2 O + CO 2 Ba(ClO 3 ) 2 BaCl O 2 Cu(OH) 2 CuO + H 2 O 2 H 3 PO 4 P 2 O H 2 O The following rules will help when determining the products of a decomposition reaction. 1. All binary compounds will break down into their elements. 2. All carbonates break down to the metal oxide and carbon dioxide gas. 3. All chlorates break down to the metal chloride and oxygen gas. 4. Metal hydroxides break down to the metal oxide and water. 5. Oxy acids break down to the non-metal oxide (with the non-metal having the same valence) and water. Practice Problems: Provide a completed word and full balanced chemical equation for each reaction. a) nickel (II) chloride g) Cs 2 CO 3 b) silver oxide h) Al(OH) 3 c) nitrous acid i) H 2 SO 4 d) iron (III) hydroxide j) RbClO 3 e) zinc carbonate k) LiCl f) carbonous acid l) Au(ClO 3 ) 3 W1

2 B) SYNTHESIS A + B AB During a synthesis reaction, two or more elements or simple compounds come together to form 1 compound. These are the reverse of a decomposition reaction. sodium + oxygen sodium oxide lead (II) oxide + carbon dioxide lead(ii) carbonate iron (II) chloride + oxygen iron (II) chlorate zinc oxide + water zinc hydroxide silicon dioxide + water silicic acid Sn + F 2 SnF 2 K 2 O + CO 2 K 2 CO 3 BeCl O 2 Be(ClO 3 ) 2 Na 2 O + H 2 O 2 NaOH SeO 2 + H 2 O H 2 SeO 3 Since synthesis reactions are the reverse of decomposition reactions, reverse the rules from above to determine the products of a synthesis reaction. 1. Two elements will react to form the binary compound. 2. A metal oxide and carbon dioxide will react to form the metal carbonate. 3. A metal chloride and oxygen will react to form the metal chlorate. 4. A metal oxide and water will react to form a metal hydroxide. 5. A non-metal oxide and water will react to form the oxy acid (with the non-metal having the same valence). Practice Problems: Provide a completed word and full balanced chemical equation for each reaction. a) magnesium chloride + oxygen g) BeO + CO 2 b) cesium + iodine h) Al 2 O 3 + H 2 O c) diphosphorus trioxide + water i) N 2 O 3 + H 2 O d) potassium oxide + water j) NaCl + O 2 e) barium oxide + carbon dioxide k) Ga + Br 2 f) silver + sulfur l) Ca + P 4 W2

3 C) SINGLE DISPLACEMENT AX + Y YX + A or AX + B AB + X During a single displacement (also called single replacement) reaction one element replaces another element in a compound forming a new compound. There are 2 different possibilities. 1. One cation replaces another: AX + Y YX + A, where both A and Y are cations (usually metals and hydrogen). For an element to displace another in a compound, it must be higher up in the activity series than the element in the compound. copper + silver nitrate silver + copper (II) nitrate calcium + water calcium hydroxide + hydrogen Fe + Cu(NO 3 ) 2 Fe(NO 3 ) 2 + Cu Zn + HCl (aq) ZnCl 2 + H 2 2. One anion replaces another: AX + B AB + X, where both X and B are anions (usually nonmetals). For an element to displace another in a compound, it must be more reactive than the element in the compound. chlorine + sodium bromide sodium chloride + bromine Br KI 2 KBr + I 2 Practice Problems: Provide a completed word and full balanced chemical equation for each reaction. a) aluminum + lead (II) nitrate g) Al + HCl b) chlorine + lithium iodide h) Zn + H 2 SO 4 c) iron + silver acetate i) Pb + AgNO 3 d) aluminum + copper (II) chloride j) Fe + CuSO 4 e) bromine + iron (III) chloride k) Li + H 2 O f) barium + water l) PbI 4 + F 2 W3

4 D) DOUBLE DISPLACEMENT AB + XY AY + XB During a double displacement (also called a double replacement) reaction, the cations and anions of two different compounds switch places. iron (II) acetate + sodium chloride iron(ii) chloride + sodium acetate 2 NaCl + H 2 SO 4 Na 2 SO HCl AgNO 3 + NaCl AgCl + NaNO 3 When an acid and base react, this is a special case of a double displacement reaction called a neutralization which forms a salt (ionic compound) and water. potassium hydroxide + sulfuric acid potassium sulfate + water 2 H 3 PO Ca(OH) 2 Ca 3 (PO 4 ) H 2 O In some cases, a product will form in the double displacement reaction that will then decompose further. Whenever H 2 CO 3, H 2 SO 3 and NH 4 OH are formed in the reaction, they will decompose to CO 2 and H 2 O, SO 2 and H 2 O and NH 3 and H 2 O respectively. calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water K 2 SO HNO 3 2 KNO 3 + SO 2 + H 2 O NH 4 Cl + NaOH NaCl + NH 3 + H 2 O Practice Problems: Provide a completed word and full balanced chemical equation for each reaction. a) calcium hydroxide + carbonic acid g) Na 2 CO 3 + H 2 SO 4 b) potassium carbonate + barium chloride h) Al(OH) 3 + HC 2 H 3 O 2 c) zinc phosphate + ammonium sulfide i) Al 2 (SO 4 ) 3 + Ca 3 (PO 4 ) 2 d) cobaltic hydroxide + nitric acid j) Cr 2 (SO 3 ) 3 + H 2 SO 4 e) silver nitrate + potassium chloride k) AgC 2 H 3 O 2 + K 2 CrO 4 f) ammonium chloride + magnesium hydroxide l) (NH 4 ) 2 SO 4 + KOH W4

5 E) COMBUSTION C x H y + O 2 (g) CO 2 (g) + H 2 O (g) or C x H y + O 2 (g) C (s) + CO (g) + CO 2 (g) + H 2 O (g) In a combustion reaction, a hydrocarbon (a compound made of carbon and hydrogen) reacts with oxygen gas. There are 2 types of combustion. 1. Complete Combustion: C x H y + O 2 (g) CO 2 (g) + H 2 O (g) 2. Incomplete Combustion: C x H y + O 2 (g) C (s) + CO (g) + CO 2 (g) + H 2 O (g) CH 4 + O 2 (g) CO 2 (g) + 2 H 2 O (g) C 3 H O 2 (g) C (s) + CO (g) + CO 2 (g) + 3 H 2 O (g) In some cases the hydrocarbon may also contain nitrogen or sulfur, in which case NO 2 or SO 2 is also produced. C 21 H 24 N 2 O O 2 (g) 21 CO 2 (g) + 12 H 2 O (g) + 2 NO 2 (g) 2 C 2 H 5 SH + 9 O 2 (g) 4 CO 2 (g) + 6 H 2 O (g) + 2 SO 2 (g) Practice Problems: Complete a balanced chemical equation for each reaction. Assume complete combustion in each. a) C 6 H 6 + O 2 (g) b) C 11 H 22 O 11 + O 2 (g) c) C 25 H 52 + O 2 (g) d) C 2 H 5 OC 2 H 5 + O 2 (g) e) C 4 H 9 OH + O 2 (g) f) C 6 H 13 SH + O 2 (g) W5

6 F) EXOTHERMIC AND ENDOTHERMIC Many reactions require or release heat and in addition to being classified as one of the types discussed above can also be classified as exothermic or endothermic. Exothermic reactions are those accompanied by a release of heat (energy) Example: 2 H 2(g) + O 2(g) 2 H 2 O (g) + Energy Endothermic reactions are those that require heat (energy) to be added for the reaction to occur. Example: CaCO 3(s) + Energy CaO (s) + CO 2 (g) MAKING CONNECTIONS: 1. Use the textbook and Internet to summarize the following concepts and their applications in everyday life: a) Catalysts and Catalytic converters (P ) b) Neutralization Reactions (P. 176 & P ) c) Extraction of Metals and Metallurgical Processes (P. 212, 217) d) Corrosion, Alloys and Corrosion Protection (P. 379) 2. Complete the following Textbook questions. P. 155 # 4, 6, 7; P. 169 # 5, 7, 9; P. 177 # 8; P. 188 # 71; P. 197 # 6, 8; P. 204 # 5, 9; P. 201 # 3; P. 217 # 6; P. 221 # 6; REVIEW - CHEMICAL REACTIONS P read over all the questions, attempt as many as possible (write solutions to questions you find challenging). W6

7 Types of Chemical Reactions 1. For each reaction below, indicate its type and then balance. a) H 2 + O 2 H 2 O b) H 2 O 2 O 2 + H 2 c) Al + H 2 SO 4 Al 2 (SO 4 ) 3 + H 2 d) CO + O 2 CO 2 e) HgO Hg + O 2 f) KBr + Cl 2 KCl + Br 2 h) Cr 2 O 3 + H 2 O Cr(OH) 3 i) Pb(NO 3 ) 2 + NaCl PbCl 2 + NaNO 3 j) NaNO 3 NaNO 2 + O 2 k) Ba(OH) 2 + H 3 AsO 4 Ba 3 (AsO 4 ) 2 + H 2 O l) C 5 H 12 O + O 2 CO 2 + H 2 O m) As 2 O 5 + H 2 O H 3 AsO 4 W7

8 2. Complete the following word equations by determining the products of the reaction, then write a balanced chemical equation and indicate the type of reaction. a) strontium bromide + fluorine b) magnesium + iron (III) oxide c) silver nitrate + zinc chloride d) nickel (III) carbonate e) tricarbon hexahydride + oxygen gas f) barium + water g) tin (II) hydroxide + phosphoric acid h) calcium chloride + oxygen i) tetraphosphorus decaoxide + water j) lithium bicarbonate + hydrosulfuric acid k) acetic acid + nickel W8

9 Mixed Practice -State the type, predict the products, and balance the following reactions: 1. BaCl 2 + H 2 SO 4 2. C 6 H 12 + O 2 3. Zn + CuSO 4 4. Cr 2 (SO 3 ) 3 + HNO 3 5. Cs + Br 2 6. FeCO 3 7. NaClO 3 8. HCl (aq) + AgNO 3(aq) 9. Bi 2 O Na 2 O 11. CaCl 2(aq) + Na 3 PO 4(aq) 12. Na 2 SO 3 + H 3 PO 4 W9

10 13. AlCl C 2 H 4 + O Pb(NO 3 ) 2(aq) + BaCl 2(aq) 16. Zn + AgNO Al + P H 2 SO 4(aq) + NaOH (aq) 19. NaI + MgS 20. Cl 2 + NaBr 21. C 6 H 12 O 6 + O KOH (aq) + CuSO 4(aq) 24. Na 2 CO 3 + H 2 SO (NH 4 ) 2 S + Cd 3 (PO 4 ) (NH 4 ) 2 S + Co(OH) 3 W10