Types of Chemical Reactions Chapter 6

6 Types Synthesis Decomposition Single displacement Double displacement Combustion Neutralization (Chapter 5)

Online Resources Animation: http://www.youtube.com/watch?v=tE4668aarck DEMOS: http://www.youtube.com/watch?v=i-HHvx1VC_8 Lessons: http://www.youtube.com/watch?v=g-biRwAVTV8 (Flintstones) http://www.youtube.com/watch?v=3vLAH4Py9zI

Synthesis This type of reaction involves the combination of multiple reactants into a single product Synthesis reactions have a general formula: F + W ➜ FW

Examples 1. Element + Element ➜ Compound 2Al(s) + 3Cl2 (g) ➜ 2 AlCl3 (s) 2. Compound + Element ➜ Compound PCl3(l) + Cl2 (g) ➜ PCl5 (s) 3. Compound + Compound ➜ Compound SO2(g) + H2O(l) ➜ H2SO4(aq)

Decomposition This type of reaction involves the splitting of a single reactant into multiple products Decomposition reactions have the general formula: FW ➜ F +W

Examples 1. Compound ➜ Element + Element 2HI(g) ➜ H2 (g) + I2 (g) 2. Compound ➜ Compound + Element 2 H2O2(l) ➜ 2H2O(l) + O2 (g) 3. Compound ➜ Compound + Compound Ca(OH)2(s) ➜ CaO(s) + H2O(l)

WORK Read section 6.1 Worksheet Page 226 to 227, ALL Practice Problems: Review Questions: Page 229 #1-10

Single Displacement This type of reaction involves an element and a compound as reactants The element displaces (replaces) one of the elements in the compound cations replace cations, anions replace anions Single displacement reactions have the general formula: FW + B ➜ FB + W

Examples Element + Compound  Element + Compound Zn(s) + CuSO4(aq)  Cu (s) + ZnSO4(aq) Mg(s) + 2AgNO3 (aq)  2Ag (s) + Mg(NO3)2(aq) Br2(g) + CaI2(aq)  I2 (g) + CaBr2(aq) 2 Na(s) + 2 H2O(l)  H2 (g) + 2 NaOH(aq) 2 Na + 2 HOH  H2 + 2 NaOH

Double Displacement This type of reaction involves two compounds as reactants Positive and negative ions in two compounds appear to “change partners” to form two new compounds with no change in oxidation numbers [ie. Copper (II) stays copper (II)]. Double displacement reactions have the general formula: FW + RB  FB + RW

Examples Compound + Compound  Compound + Compound HCl(aq) + NaOH(aq)  NaCl (aq) + H2O(l) 2H3PO4 (aq) + 3 Ca(OH)2 (aq)  Ca3(PO4)2 (s) + 6H2O (l) MnS(s) + 2HCl(aq)  MnCl2 (aq) + H2S(g)

WORK Read pages 233 to 236 Finish Worksheet Page 233 to 235, ALL Practice Problems Review Questions: Page 240 #1-12

Combustion Combustion is a very rapid reaction of a substance with oxygen to produce compounds called oxides. We often call this process burning. The following word equation represents a general combustion reaction: fuel + oxygen  oxides + (energy)

Hydrocarbons Hydrocarbons (compounds with H, C) are the most important fuels that we burn! Gasoline, natural gas (methane), propane, kerosene and matches. When these burn, the products are mostly CO2 and H2O which are released into the atmosphere. These can contribute to the green house effect.

Common Hydrocarbons FORMULA COMMON NAME CHEMICAL NAME CH4 Methane Carbon tetrahydride C3H8 Propane Tricarbon octahydride C4H10 Butane Tetracarbon decahydride

Burning Propane Complete combustion Incomplete combustion Propane + oxygen  carbon dioxide + water C3H8 + 5O2  3CO2 + 4H2O Incomplete combustion Propane + oxygen  carbon dioxide + water + carbon monoxide + carbon 2C3H8 + 7O2  2CO2 + 8H2O + 2CO + 2C

Complete vs. Incomplete Combustion of Hydrocarbons Occurs when the right amount of O2 is available to react with the fuel and all the carbon in the fuel is converted into CO2. The only products are CO2 and H2O. Incomplete combustion: This occurs when there is not enough oxygen available to react with the fuel four products are produced instead of two: CO2, CO, C, H2O Carbon monoxide is a colourless, odourless, and poisonous gas that can can combine with the haemoglobin in the blood to starve the body of oxygen and cause death!!! Carbon is the black residue (soot) that you see in fireplaces.

Combustion of metals 2 Ca + O2  2 CaO Combustion & synthesis

Combustion of Non-metals N2 + 2 O2  2 NO2 Combustion & synthesis

Homework Read pages 230 to 232 Page 240 # 9 & 11 Page 242 # 11 & 13

Neutralization A neutralization reaction is a special case of double displacement reaction between an Acid and a Base. The products of a neutralization reaction are always water and a salt (ionic compound). Examples: 1. HCl(aq) + NaOH(aq)  HOH + NaCl Hydrochloric acid + sodium hydroxide  water + sodium chloride 2. H2SO4(aq) + 2KOH  2H2O + K2SO4 Sulfuric acid + potassium hydroxide  water + potassium sulfate During a neutralization reaction, the hydrogen ion from the acid reacts with the hydroxide ion from the base H+ + OH-  H2O

Homework Read Section 5.2 Worksheet