Synthesis Decomposition Single Replacement Combustion Redox Reactions Synthesis Decomposition Single Replacement Combustion
objective I can classify redox reactions so I can recognize patterns of chemical behavior and predict the products of reactions.
Redox Reaction Review In an oxidation – reduction reaction (or Redox reaction), electrons are lost by one element and gained by another element. Reactions that involve elements as reactants or products are always redox. EX. Mg (s) + O2 (g) MgO(s)
Which of the following is a redox reaction? 2K(s) + Cl2(g) → 2KCl(s) H2O2(aq) → H2O(l) + O2(g) 2Al(s) + 3Cu(SO4)(aq) → 3Cu(s) + Al2(SO4)3(aq) CH4(g) + O2(g) → CO2(g) + 2H2O(l) all of the above are redox reactions [Default] [MC Any] [MC All]
Redox Reactions We classify chemical reactions so that we can recognize patterns of chemical behavior, and predict the products that will form. The following four types of reactions are all considered Redox Reactions. Synthesis A + B AB Decomposition AB A + B Single Replacement A + BC B + AC Combustion CxHy + O2 CO2 + H2O
Synthesis Redox Reaction A + B AB two or more substances combine to form a single substance. The two reactants are frequently a Metal and a non-Metal. The product that they form is then a(n) ionic compound. To write the correct formulas for ionic compounds, we use the criss-cross method.
Synthesis Redox Reaction A. Group A metals and a nonmetal react with each other to produce a compound made up of a metal cation and a nonmetal anion. __K + __Cl2 ________ __K + __Cl2 __KCl 2K + Cl2 2KCl
Synthesis Redox Reaction A. Group A metals and a nonmetal react with each other to produce a compound made up of a metal cation and a nonmetal anion. __K + __Cl2 ________ __K + __Cl2 __KCl 2K + Cl2 2KCl
Synthesis Redox Reaction B. More than one product is also possible when a transition metal and a nonmetal react. Fe + S FeS iron(II) sulfide 2Fe + 3S Fe2S3 iron(III) sulfide
Synthesis Redox Reaction C. When two nonmetals react by synthesis, more than one product is often possible. S + O2 SO2 sulfur dioxide 2S + 3O2 2SO3 sulfur trioxide
Which of the following represents a synthesis reaction? AB A + B A + BC B + AC A + B AB AB + CD CB + AD [Default] [MC Any] [MC All]
Which of these is a synthesis redox reaction? CH4(g) + O2(g) → CO2(g) + 2 H2O(l) 2H2O2(aq) → 2H2O(l) + O2(g) 2K(s) + Cl2(g) → 2KCl(s) [Default] [MC Any] [MC All]
Decomposition Redox Reaction AB A + B In a decomposition reaction, a single compound is broken down into two or more products. The reactant: a single compound The products: more than one element or compound. Most decomposition reactions require a catalyst in the form of a chemical, heat, light, or electricity.
TNT C7H5N3O6 TNT is one of the most commonly used explosives for military and industrial applications. 2 C7H5N3O6(s) → 3 N2(g) + 5 H2(g) + 12 CO(g) + 2 C(s)
Which of these is a decomposition reaction? CH4(g) + O2(g) → CO2(g) + 2 H2O(l) 2H2O2(aq) → 2H2O(l) + O2(g) 2K(s) + Cl2(g) → 2KCl(s) [Default] [MC Any] [MC All]
Lab Demonstrations Synthesis Reaction: Decomposition Reactions: “Iron reacts with oxygen to produce iron (III) oxide (rust)” Iron + oxygen iron(III) oxide ____Fe(s) + ____O2(g) ____Fe2O3 (s) Decomposition Reactions: “Hydrogen peroxide decomposes to form water and oxygen gas.” Hydrogen Peroxide water + oxygen ____H2O2 (aq) ____H2O(l) + ____O2(g) “In the presence of electricity, water decomposes to form oxygen and hydrogen” ____H2O(l) ___H2(g) + ___ O2 (g)
REdox Reactions part II Single Replacement Combustion REdox Reactions part II
Single-Replacement Reactions A + BC B + AC A metal element replaces a second metal element in the compound. “A replaces B” AC and BC are ionic compounds Example: 3 Mg (s) + 2 AlCl3 (aq) 2 Al (s) + 3 MgCl2 (aq)
Which of the following represents a single replacement reaction? AB A + B A + BC B + AC A + B AB AB + CD CB + AD [Default] [MC Any] [MC All]
Which of the following is a single replacement redox reaction? 2 K(s) + Cl2(g) → 2 KCl(s) H2O2(aq) → H2O(l) + O2(g) 2 Al(s) + 3 Cu(SO4)(aq) → 3 Cu(s) + Al2(SO4)3(aq) CH4(g) + O2(g) → CO2(g) + 2 H2O(l) none of the above [Default] [MC Any] [MC All]
Single Replacement Reactions A + BC B + AC Not all single replacement reactions can occur. Whether one metal will replace another metal from a compound can be determined by the relative reactivities of the two metals.
Single Replacement Reactions A + BC B + AC A reactive metal will only replace a metal listed below it in the Activity Series. Mg(s) + Zn(NO3)2(aq) Mg(s) + Li(NO3)(aq)
Single Replacement Reactions A + BC B + AC A reactive metal will only replace a metal listed below it in the Activity Series. Mg(s) + Zn(NO3)2(aq) Mg(NO3)2(aq) + Zn(s) Mg(s) + Li(NO3)(aq) no reaction
Which of these is higher on the activity series? calcium magnesium [Default] [MC Any] [MC All]
Which of these is higher on the activity series? hydrogen magnesium [Default] [MC Any] [MC All]
Mg(s) + 2HCl(aq) H2(g) + MgCl2(aq) A reactive metal will only replace a metal listed below it in the Activity Series. Which of these reactions will NOT occur? Mg(s) + 2HCl(aq) H2(g) + MgCl2(aq) H2(g) + MgCl2(aq) Mg(s) + 2HCl(aq) [Default] [MC Any] [MC All]
Can this single replacement reaction occur Can this single replacement reaction occur? “aluminum reacts with rust to produce iron and aluminum oxide” 2Al(s) + Fe2O3(s) 2Fe(s) + Al2O3(s) Yes No
Combustion Reactions
Combustion Reactions CxHy + O2 CO2 + H2O + energy A. In a combustion reaction, a compound reacts with oxygen to produce energy as heat, light or electricity. B. Reactants: hydrocarbons (compounds of hydrogen and carbon) and oxygen Products: carbon dioxide and water
Which of these is always the products of a combustion reaction? oxygen and heat hydrogen and oxygen water and carbon dioxide carbon dioxide and oxygen [Default] [MC Any] [MC All]
You observe the combustion of butane C4H10…… You observe the combustion of butane C4H10……. Which of these reactants must also be present? C4H10 water carbon dioxide gas oxygen gas hydrogen gas [Default] [MC Any] [MC All]
Combustion reaction Example: CH4 (g) + 2O2 (g) CO2 (g) + 2H2O
Hydrocarbon molecule examples - CxHy propane C3H8 methane CH4 octane C8H18
Which of the following represents a combustion redox reaction? AB A + B A + BC B + AC HxCy + O2 CO2 + H2O A + B AB AB + CD CB + AD none of the above [Default] [MC Any] [MC All]
Which of these is a combustion reaction? C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l) 2H2O2(aq) → 2H2O(l) + O2(g) 2K(s) + Cl2(g) → 2KCl(s) [Default] [MC Any] [MC All]
Redox Lab Demos Single Replacement: aluminum reacts with iron(III)oxide to replace the iron and forms aluminum oxide __Al(s) + __Fe2O3(s) __Fe(s) + __Al2O3(s) Combustion: Propane (C3H8) reacts with oxygen to produce carbon dioxide gas, water and heat. __ C3H8 + __O2 __ CO2 + __H2O + heat Ethyl alcohol reacts with oxygen to produce carbon dioxide gas and water